Large scale new energy access to weak alternating current (AC) power grid is prone to transient overvoltage,phase-locked synchronous stability and other problems,which bring problems for the full use of new energy. In this paper,the influencing factors of the stability level of the new energy access system are explored. The short-circuit ratio index of new energy is used as the quantitative evaluation basis of the system voltage intensity,and the sensitivity of the short-circuit ratio of new energy generation power is derived. The comprehensive sensitivity index of the short-circuit ratio of new energy is constructed by comprehensively considering the sensitivity of the average short-circuit ratio and the lowest short-circuit ratio of the system,and an optimal power allocation control scheme for new energy generation based on equal comprehensive sensitivity criterion is proposed. Based on this method,the optimal control of new energy power generation is carried out,and the full utilization of renewable energy is realized on the basis of ensuring the security and stability of the system. Finally,the feasibility and effectiveness of the proposed method are verified by taking a new energy centralized transmission system in Northwest China as an example.