Abstract: In order to comprehensively understand the effects of grading crossing between Dorper sheep and Hu sheep, in the experiment, purebred black-headed Dorper sheep were selected as the male parent to cross with Hu sheep（ Dorper × Hu group and the offspring is recorded as F1 generation）, F1 generation of Du × Hu sheep（ Dorper ×F1 group and the offspring is recorded as F2 generation） and F2 generation of Du × Hu sheep（ Dorper ×F2 group and the offspring is recorded as F3 generation）, respectively, and the pure-bred Hu sheep group and the pure-bred Dorper sheep group were used as the controls. The body shape and appearance of offspring lambs in each group were observed. The reproductive performance（including number of lambs, number of live lambs, number of twin-lambs, number of multiple-lambs, lamb rate, lamb survival rate, twin-lamb rate and multiple-lamb rate）, production performance（lamb birth weight, lamb weight at 1, 2, 3, and 6 months old, average daily gain from 1 to 6 months old, and body length, height and chest circumference of 6-month-old lambs）, slaughter performance（pre-slaughter body weight, carcass weight, slaughtering rate, eye muscle area, and GR value）, immune indexes（Ig, IL and IFN）, and meat quality(pH_{45 min}, pH_{24 h}, meat color, marble pattern, water loss rate, cooked meat rate, and shear value) of offspring lambs and the sensory assessment indexes of mutton carcass（carcass characteristics, carcass weight, fatness, meat hardness, muscle development, meat fat color, cooking methods） were determined. The results showed that with the increase of cross breeding generations, the body shape and appearance of lambs clearly tend to be similar to those of Dorper sheep.The lambing percentage of ewes in Dorper ×F1 group, Dorper ×F2 group and pure-breeding Hu sheep group was lower than that in Dorper × Hu group and pure-breeding Hu sheep group, and the lambing percentage of pure-breeding Hu sheep group was the highest. The lamb survival rate in Dorper × Hu group was the highest. The twin rate was the highest in pure-breeding Hu sheep group. The multiple birth rate in Dorper × Hu group and pure-breeding Hu sheep group was higher than that in Dorper ×F1 group, Dorper ×F2 group and pure-breeding Hu sheep group. The twin rate in pure-breeding Dorper sheep group was 54.88%, but the multiple-lamb rate was 0. With the increase of hybrid generation, the growth rate of F1 generation, F2 generation and F3 generation generated by the cross between Dorper and Hu sheep gradually accelerated, and the growth rate of F3 generation was the fastest, which was close to the growth rate of purebred Dorper sheep. The chest circumference, body height and body length of male and female lambs were also improved. The carcass weight and slaughtering rate in Dorper ×F1 group, Dorper ×F2 group and pure-breeding Dorper sheep group were significantly higher than those in pure-breeding Hu sheep group（P＜0.05）, but there were no significant differences in pre-slaughter weight, eye muscle area and GR value among all groups（P＞ 0.05）. The serum IgA mass concentration in pure-breeding Hu sheep group was significantly higher than that in pure-breeding Dorper sheep group（P＜0.05）, and the serum IL-2 mass concentration in pure-breeding Hu sheep group was significantly higher than that in Dorper ×F2 group and pure-breeding Dorper sheep group（P＜0.05）. The serum IL-6 mass concentration in pure-breeding Hu sheep group and Dorper × Hu group was significantly higher than that in pure-breeding Dorper sheep group（P＜0.05）, and there was no significant difference in the serum IgG, IgM, IL-1β, IL-4 and IFN-γ mass concentration among all groups（P＞0.05）. There was no significant difference in meat quality indexes among all groups（P＞0.05）. The pH_45min value was between 6.15 and 6.35, and the pH_24h value was between 5.69 and 5.90. The pure-breeding Hu sheep had the hightest score of marble and the lowest water loss rate. The 6-month-old lambs in pure-breeding Hu sheep group have small carcass, thick fat and lower lean meat percentage, which were suitable for cooking in soup and stew. The breast and hip muscles of the 6-month-old lambs in Dorper × Hu crossbred group were plump, the meat fat was firm. The belly fat was milky white, with fat content suitable for cooking hand-grasped mutton and instant-boiled mutton. The 6-month-old lambs in Doper×F1 group, Dorper ×F2 group and pure-breeding Dorper sheep group had good carcass quality, plunp breast and buttock muscles, and high lean meat percentage. It was suitable for instant-boiled mutton and hand-grasped mutton cooking processing. The results indicated that the crosses superiority of Dorper sheep and Hu sheep was obvious, the cross breeding could be used to produce commercial mutton sheep, and also to breed new breeds or new strains of high-quality mutton sheep.