In order to find out the analytical quality for pesticide residue by different institutions in China, two 666 and DDT quality control samples were used in the work of analytical quality assurance in May, 2002. The results indicated that among the data obtained by 13 institutions, the proportion of disqualification detection data reached 16 5%. Seven of 13 institutions provided the eligible data but 3 did not. It suggests that quality control analysis should be carried out frequently so as to keep the results accurate.