To investigate the application of bromocresol green Colorimetry (BCG) method in measuring serum albumin (ALB) and to evaluate its influencing factors in different diseases. This study was a cross-sectional study that included 128 people admitted to the department of nephrology, department of general surgery, department of infectious diseases and other departments of the Third Xiangya Hospital of Central South University in July 2021. They were divided into groups according to disease types, including chronic kidney disease group (47 cases), liver disease group (40 cases), other diseases group (41 cases), serum ALB was detected by BCG method and immunoturbidimetry at the same time, and the results were expressed as ALB and ALB respectively, each group was subdivided into three subgroups according to ALB results: relatively high-value subgroup, relatively intermediate-value subgroup and relatively low-value subgroup of albumin. ALB and ALB were compared in all groups and subgroups. Passing-Bablok regression and Bland-Altman diagram analysis were used to evaluate the application of ALB in each group. Immunoturbidimetry was used as a reference method to evaluate the bias of ALB, and the differences between ALB and ALB were shown as follows:ALB= ALB-ALB. Pearson correlation analysis and multiple linear regression analysis were used to assess the correlation between ALB and ALB autoconcentration (ALB), α-globulin, α-globulin, β-globulin, β-globulin, γ-globulin, creatinine (Cr), urea (UN), uric acid (UA), aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin (TBil), direct bilirubin (DBil), and C-reactive protein (CRP) levels.The results showed that ALB were higher than ALB in the relative low subgroups of total patients group, chronic kidney disease group, liver disease group and other disease groups, and the differences were statistically significant ( value was 8.025, 6.878, 2.628, 4.915, respectively, <0.05). In the relatively high value subgroup, ALB was lower than ALB, and the differences were statistically significant in the relative high value subgroup of total patients group, liver disease group and other disease groups ( value was -4.388, -2.927, -3.979, <0.05). Passing-Bablok regression and Bland-Altman analysis showed that the BCG method had proportional bias. In the chronic kidney disease group, the concentrations of ALB and Cr had the greatest influence on BCG bias, and the regression model equation was ALB=5.437-0.146× Alb-0.001 ×Cr, ²=0.505. In the liver disease group, the concentrations of ALB, α-globulin, β-globulin had the greatest influence on BCG bias, and the regression model equation was ALB=3.652-0.230×ALB+0.398×α-globulin+1.171×β-globulin, ²=0.658. In the other disease group, the concentration of ALB and α-globulin had the greatest influence on BCG bias, and the regression equation was ALB=5.558-0.225×Alb-0.281×α-globulin, ²=0.646. The BCG method has a proportion error, and its bias may lead to unacceptable differences. BCG method is mainly affected by the concentration of ALB itself, and may also be affected by α-globulin, α -globulin, β-globulin, Cr.