To control the accuracy of examination data in certain scope and ensure the related hygienic microbiological laboratory issues the accurate data, gelatin piece of bacteria was adopted as the contrast for quality control. The colony count of such gelatin pieces and filter paper pieces selected randomly were tested and their mean values of relative standard deviation ( RSD ) indicated that gelatin piece of bacteria provided more accurate result than the latter. Meanwhile, such wafers in one room and in different rooms and kept for different days were counted respectively, the results revealed that there were no remarkable difference among them. The results show that the gelatin piece of bacteria is appropriate for colony counting as contrast.