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 being popularized in Xiang’an District of Xiamen City was screened, in order to provide technical support for the promotion of new fertilizer. The single factor randomized block design was used in the experiment. The common variety Pushu 32 in Xiang’an District was used as the test material, and four treatments were set up. The base fertilizer of treatment 1 (CK, traditional fertilizer application of farmers) was 450 kg·hm⁻² potassium sulfate compound fertilizer, and the base fertilizers of treatments 2 to 4 were 360, 585, and 810 kg·hm⁻² compound microbial fertilizers, respectively. And the topdressing fertilizers of each treatment were 375 kg·hm⁻² potassium sulfate compound fertilizer. 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 economic benefit was the best when the total fertilizer application rate was reduced by 15% compared with that of treatment (CK), which could be further tried and popularized in the main producing areas of local sweet potato in Xiamen.