Abstract: A non-reduced SDS-PAGE purity method for quantitation of conbercept fragments was established based on gel screening, comparison of gel imaging system, linearity range of main band, screening of destaining conditions. The results indicated that the bands could be separated effectively with good clearness and flatness on 4%-15% gradient concentration gel, the peaks of all bands could be separated from baseline using high-distinguishability gel imaging system, the signal intensity of a main band had shown a good linearity with ≤ 3 μg of loading amount, and that the destaining was set as a total of ≤ 3 h with exchanging 100 mL destaining buffer every 60 min. The established non-reduced SDS-PAGE method could demonstrate the purity of conbercept more objectively. After validation, the established non-reduced SDS-PAGE method was submitted to FDA in the form of supplementary materials, which laid a quality basis for the direct entry of conbercept to the clinical Ⅲ study in the United States.