Abstract: Taking local walnut trees as test materials,to take photos to record the changes of fruit appearance and morphology.Fruit weight,fruit diameter,nut weight,kernel weight,kernel rate,oil content,and fatty acid composition in mature kernel were measured and analyzed.The aim of this study was to elucidate dynamic change of walnut fruit growth and development and kernel oil accumulation.The results indicated that with the growth and development of walnut fruit,fruit weight,fruit diameter,nut weight,kernel weight,kernel rate,oil content was increasing with time.The fruit weight decreased slightly in the later stage of ripening.Mathematical equations of growth and development of walnut were established.In the middle of July,the kerneloil began to accumulate and gradually increased,and the oil content in the kernel reached the maximum value of 69.4% when the fruit was mature.The main fatty acids in mature seed kernel were palmitic acid,stearic acid,oleic acid,linoleic acid and linolenic acid,and the content of unsaturated fatty acids reached 91.7%.In mid September,walnut fruit wasfully mature,and the oil content was the highest,which was the best harvest time.According to the walnut fruit morphological characteristics,fruit growth curve and mathematical equations,the fruit development period could be judged,and reasonable cultivation and management measures can be taken to improve the yield and quality of walnut fruit.