Viscoelastic particle oil displacement agents （including PPG and B-PPG） have both partially cross-linked structure and partially branched molecular structure. The content of cross-linked network structure greatly influences their oil displacement performance，and is a core characteristic parameter for evaluating the performance of this type of oil displacement agent. However，there is still a lack of effective characterization methods for the cross-linked network structure content of PPG and B-PPG products. In this paper，a quantitative detection method based on complexant chelation combined with liquid chromatography was established to determine the cross-linked network structure content of PPG and B-PPG. First，the gel particles in PPG and B-PPG dispersions were fully crushed，then aluminum nitrate was used as complexant to chelate and eliminate the interference of linear structure in the system. Combined with liquid chromatography detection of the change of polymer peak area during the chelation process，it was confirmed that the chelation process presented a three-stage characteristic with the increase of aluminum nitrate dosage. After the completion of the first stage，the ratio of the minimum polymer chromatographic peak area to the original peak area was the cross-linked network structure content of PPG and B-PPG. The established method was applied to test actual viscoelastic particle oil displacement agent samples，the results showed that the cross-linked network structure content of B-PPG was about 86 %，and that of PPG was about 25 %，the proportion of cross-linked network structure in B-PPG was significantly higher than that in PPG. This method can achieve accurate quantification of the cross-linked network structure content of viscoelastic particle oil displacement agent，and provide an important technical means for performance optimization and quality control of this type of oil displacement agent.