Abstract: The strength of the power system with renewable energy generation (REG) is weak and the post-fault steady-state voltage security problem is prone to occur. Considering the interaction among the multi-infeed branches, a quantitative analysis model based on the voltage security constraint is established by using the short-circuit ratio (SCR) as system strength index. First, a post-fault steady-state voltage analysis model of the single-infeed system is established. Furthermore, the analysis model of the multi-infeed system is established to improve the practicability considering the influence among the multi-infeed branches. Then, the correlation between the SCR and the post-fault steady-state voltage security problem is quantitatively analyzed. Furthermore, taking 0.9pu as the voltage security constraint, the calculation method of the minimum short-circuit capacity and the quantification method of the maximum REG scale are proposed. Finally, the accuracy of the post-fault steady-state voltage security analysis model, the minimum short-circuit capacity and the quantification method of the maximum REG scale are verified by simulations, which provides the reference for the safe and stable operation of the power system with REG.