Objective To investigate the influence of HCG sample dilution on its detection results and to optimize the detection flow sheet and acquire accurate test results. Methods The 35 blood samples from patients were randomly collected and the HCG concentration in original samples or diluted with 50 times solution samples were detected by chemiluminescence immunoassay with Roche cobas e601. Results At the HCG levels was lower than 1770 mIU/mL, the HCG concentration detected by diluted method was lower than that of original samples. On the other hand, the HCG detected results with dilution method was higher than original samples detection. The detected results with dilution method needed to rectify by the formulas. Conclusion In order to ensure the accuracy of the HCG detection result, the appropriate detection mode should be chosen and the result should be rectified based on the detection model.