OBJECTIVE： To investigate the microbial contamination of the different medicinal parts of 10 kinds of TCM decoction pieces in Beijing. METHODS： By microbial limit test stated， total aerobic microbial count （TAMC）， total yeasts and molds count （TYMC）， heat-resistant strains count and bile-tolerant Gram-negative bacteria count of 100 batches of 10 kinds of TCM decoction pieces were determined， and loading amount of 6 kinds of pathogenic bacteria were also tested. RESULTS： lgTAMC of sample ranged 2-7， and lgTYMC ranged 1-6； the detection rate for heat-resistant strain was 100％； the detection rate for bile-tolerant Gram-negative bacteria was 27％； Escherichia coli was found in 2 batches of Angelica sinensis； Salmonella shigella， Hemolytic streptococcus， Hemolytic streptococcus， Staphylococcus aureus and Pseudomonas aeruginosa was not found in all TCM decoction pieces. CONCLUSIONS： The microbial load of different types of TCM decoction piece were greatly different in Beijing area. It is suggested to formulate suitable microbial limit standard in new edition of pharmacopoeia according to medicinal part， drug property， processing technology.