Power system reliability evaluation is a high-dimensional nonlinear problem, which is difficult to be nested into the power system expansion planning model. This paper presents a power system expansion planning model and its solution algorithm based on load feasible region model and reliability tracking. Firstly, an approximate distance algorithm is proposed based on load feasible region. The approach transforms the optimization problem of load shedding calculation required into an equation solving. On this basis, the analytical expression of reliability sensitivity to components’ capacity is obtained. The reliability tracking oriented to capacity are obtained. Finally, a reliability-oriented capacity expansion planning model is proposed, and a solution algorithm based on reliability tracking and greedy algorithm is proposed. The results show that the approximate distance model can effectively reduce the computational complexity of reliability evaluation; the sensitivity model can accurately reflect the influence of equipment capacity on system reliability; the capacity expansion planning model and algorithm can achieve optimal system capacity expansion planning results.