Abstract: The field application effect of compound microbial fertilizer replacing part of compound fertilizer was studied, and the fertilizer ratio of new sweet potato fertilizer suitable for promotion in Xiang 'an District of Xiamen City was screened to provide technical support for the promotion of new fertilizer. The common variety Pushu 32 in Xiang 'an District was used as the test material, and four treatments were set up. Among them, treatment 1 was the farmer 's customary fertilization blank control（ CK ）: base fertilizer 450 kg·hm ^{− 2} balanced compound fertilizer + compound fertilizer 375 kg·hm ^{− 2}; treatment 2: 360 kg·hm⁻² compound microbial fertilizer + 375 kg·hm⁻² compound fertilizer; treatment 3: compound microbial fertilizer 585 kg·hm ^{− 2} + compound fertilizer 375 kg·hm ^{− 2}; treatment 4: compound microbial fertilizer 810 kg·hm⁻² + compound fertilizer 375 kg·hm⁻². The effects of different compound microbial fertilizers on the agronomic traits, yield and economic benefits of sweet potato were analyzed. The results showed that the application of compound microbial fertilizer was beneficial to promote the effect of sweet potato more tubers and increase the rate of large and medium tubers, but when the amount was too much, the number of tubers per plant and the rate of large and medium tubers would decrease, and the cost of fertilizer would increase. Under the treatment 3: the application amount of compound microbial fertilizer was 585 kg·hm⁻² + compound fertilizer 375 kg·hm⁻², the total fertilizer application amount was reduced by 15% compared with CK, and the economic benefit was the best. It can be further tried and popularized in the main producing areas of local sweet potato to summarize the best fertilizer application amount and corresponding supporting technology.