An interval optimization method considering tolerance design is proposed to solve the uncertainty optimization problem of interior ballistics of cased telescoped ammunition. Firstly, the interval optimization model of the interior ballistics of the cased telescoped ammunition considering tolerance design is constructed. The interval optimization model of the interior ballistics of the cased telescoped ammunition considering tolerance design under uncertainty is presented. Then, considering the extremely low computational efficiency of the interval uncertain optimization, the back propagation neural network surrogate model is introduced. A series of pareto optimal solution is obtained by using non‐dominated sorting genetic algorithm II. Through the given design scheme, it provides a reference for the optimization of the interior ballistic performance of the cased telescoped ammunition under uncertain condition.