In order to evaluate the maximum carrying capacity of new energy sources in the existing flexible interconnected distribution network, the original model is usually transformed into a mixed integer second-order cone optimization model. However, the second-order cone relaxation conditions are harsh, the generality is not high, the solution convergence is poor, and the model solution speed is slow, which cannot adapt to the fast evaluation of large-scale complex distribution networks. Therefore, a new energy carrying capacity evaluation model based on improved DC power flow algorithm is proposed, which transforms the original nonlinear model into an approximate linear model, improves the solving speed and accuracy of the model, and meets the requirements of rapid evaluation and analysis of new energy carrying capacity of flexible interconnected distribution network. The effectiveness of the proposed method is verified by IEEE 33-node distribution network and 1 000 random simulation examples, and the accuracy and numerical stability of the proposed improved DC power flow algorithm are compared and verified.