With the acceleration of the work of electric energy substitution in China, a large number of multiple electric energy substitution loads have been connected, which has brought great challenges to the safe and stable operation of the distribution network. Assessment of load hosting capacity is of great significance to the distribution network planning. Firstly, the main load types of electric energy substitution are analyzed, and their operation models are established. Then, taking the maximum load capacity of the distribution network as the objective function, considering the flexible resource operation constraints of source network load storage side and the safe and stable operation constraints of the distribution network, an optimization model for the load hosting capacity of the distribution network is established, which is transformed into a second- order cone programming model through the second- order cone relaxation method. Finally, through the simulation of a 141 node example of an actual power grid, the quantitative evaluation of the load hosting capacity of the distribution network is realized,and the role of the optimal scheduling and load regulation capacity of flexible resources in improving the load hosting capacity of the distribution network is verified.