Abstract: A method based on diafiltration-extraction and UV spectrophotometry was established for the determination of the solid content of W/O polymer emulsion. The polymers in the W/O emulsion were extracted by diafiltration-extractation method. Then a series of standard polymer solution were prepared and the absorbance of the solutions was measured by UV spectrophotometer. Linear regression equation between mass concentration and absorbance was established with correlation coefficient of 0.997 1. The absorbance of the polymer emulsion solution was tested and the corresponding mass concentration and solid content of the polymer emulsion were calculated, with RSD less than 0.30%.