Objective To find out the proficiency of provincial-level food inspection agencies on food testing; and to improve the accuracy, reliability and comparability of testing results. Method Criteria for evaluating the testing results were based on the Z scores: Z ≤2 for satisfactory results; 2＜ Z ＜3 for uncertain results and Z ≥3 for unsatisfactory results. Results The samples for quality control were delivered to 31 provincial-level food inspection agencies, 29 of them submitted results back on time (93.55%). The satisfactory, uncertain and unsatisfactory results for sulfur dioxide test were 87.10%, 3.23% and 9.68%; and that for tartrazine were 80.65%, 9.68% and 9.68% respectively. The satisfactory results for ponceau 4R, sunset yellow and amaranth were all 93.55%. Conclusion Through inter-laboratory comparison, provincial-level food inspection agencies recognized the problems in the process of testing, found out the cause of uncertain and unsatisfactory results, and conducted effective corrections to ensure the accuracy of the data issued in their reports.