Measurement uncertainty is the index to evaluate the measurement level and the basis to determine the quality of measurement results.All measurement results inevitably have uncertainty.Uncertainty is the uncertainty of the measured value due to the existence of measurement error,and the detection of coliform is no exception. According to the national standard,the evaluation method of measurement uncertainty and the international common Poisson theory,the uncertainty of detection results of coliform bacteria in milk was evaluated.By analyzing the sources of uncertainty affecting the detection results of plate counting method of coliform bacteria in milk,a simple and applicable evaluation method of plate counting uncertainty of coliform bacteria was established.