Objective：To investigate the comparability among different biochemical testing systems in the same laboratory by perform－ing the comparative analysis and bias estimation on the results. Methods：According to NCCLS document EP9-A2，3 biochemical test－ing systems including system 2 and 3（Y1-Y2，comparative testing systems） and system 1（X，targeted testing system，which was com－posed of Hitachi 7600 biochemical analyzer P1，maker reagents，c.f.a.s. calibrator and BIO RAD quality control） were used to obtain correlation coefficient and linear regression equation. The values of aspartate aminotransferase（AST），alamine aminotransferase（ALT），gamma-glutamyl transferase（GGT），alkaline phosphatase（ALP），Urea，creatinine（Cr） and uric acid（UA） in patient’s serum were de－tected by the three systems. Then the coefficient and the equation were used to evaluate the system bias between comparative testing systems and targeted testing system. The comparability of different testing systems was judged by half of the CLIA’88 standard. Re－sults：The results of the three testing systems were significantly correlated（r2>0.95）. The results of all testing items showed good comparability except those of Urea（with low concentration level） tested by system 2（Y2） and system 1（X） （%SE>1/2CILA’88 TEa）. Conclusions：There is good comparability among the results of AST、ALT、GGT、ALP、Cr、UA detected by different testing systems in our hospital except those of Urea with low concentration level.