Objective To understand the status quo of hierarchical diagnosis and treatment effect of medical alliance in Beijing and explore the influencing factors.Methods The convenience sampling method was used to select 26 vertical medical alliances,and the weighted TOPSIS method was used in combination with the index system established in the previous study to evaluate the effect of hierarchical diagnosis and treatment.The factors influencing the effect of hierarchical diagnosis and treatment in medical alliances were summarized through interviews with insiders,and the rank sum test was used to explore the factors influencing the effect of hierarchical diagnosis and treatment in medical alliances.Results The medical alliance B,A2 and A3 ranked high,and the implementation effect was relatively good in the four dimensions of"primary care first consultation,dual-way referral,acute and slow treatment,and vertical linkage";The C2,A8 and F2 medical alliances ranked low,and the implementation effect in the dimensions of"dual-way referral","acute and slow treatment"and"vertical linkage"was significantly lower than that of other medical alliances.The analysis results showed that the differences in the support intensity and core hospital level of different medical alliances were statistically significant(P＜0.05),which affected the hierarchical diagnosis and treatment effect of medical alliances.Conclusion While strengthening the information construction and improving the initiative of grassroots and the signing rate of family doctors,it is necessary to improve the support of core hospitals to promote the sinking of resources.Core hospitals should optimize resource allocation according to local conditions and promote hierarchical diagnosis and treatment.