Objective The aim of this study was to investigate the microbial contamination situation in infant formula powder during the processes of production. Methods A total of 880 samples were collected from Gansu Province, which included raw materials, manufacturing facilities, personnel swabs and final infant formula powder. The detection method conducted in this study were complied with the standard of the SN/T 0738-1997 and GB 4789, and the microbial species detected in this study included Enterobacteriaceae, Enterobacter sakazakii, and Bacillus cereus. Results The detection rate of Enterobacteriaceae was 28.41%(250/880), the detection rates of Enterobacter sakazakii and Bacillus cereus were 0.46%(4/872) and 16.94%(31/183) respectively. The prevalence of Enterobacteriaceae (40.00%,40/100) was the highest in raw materials. Four Enterobacter sakazakii strains were isolated from the pretreatment workshop, equipment and environment surface. The prevalence of Bacillus cereus was 22.73%(10/44) in final product. Conclusion The microbial contamination was existent widely in infant formula powder and the production procession. Rigid laws and managements should be conducted to reduce the microbial contamination in raw materials, production processes and the environment, which might improve the quality of infant formula powder.