Abstract: Through the comparative test of 69 groups of ferronickel slag（FNS） admixture cement and fly ash admixture cement, the effects of the content of FNS and the different ratio of FNS to silica fume on the compressive strength and flexural strength of composite cement mortar are studied. At the same time, the comparative test is carried out with the same amount of fly ash admixture. The test results show that FNS has pozzolanic activity similar to fly ash and can be used as cementitious material instead of some cement. Under the condition that the total dosage does not exceed 30%, whether it is single-doped FNS or fly ash, or double-blended FNS ＆ silica fume, or double-blended fly ash ＆ silica fume, the compressive strength and flexural strength properties of the cement glue prepared by the two sand are comparable. With the increase of FNS content, the compressive strength and flexural strength of composite FNS cement mortar gradually decrease. The total content of FNS and silicon powder in cement should not exceed 30%, whether it is single or double mixed with FNS and silicon powder. When the ratio of FNS to silica fume is 2∶1, 1∶1 and 1∶2 respectively, the strength relationship under the three ratios satisfies 2∶1＞1∶1＞1∶2.