Abstract: Techniques for calculating the saddle-node bifurcation point（SNBP） of power flow equations are fundamental to steady-state voltage stability analysis.In power system,the Moore-Spence equation has been used to calculate the SNBP of power flow equations,the dimension of which is about the twice that of the general power flow equations.This paper presented an efficient method to solve the Moore-Spence equation with the block elimination（BE） algorithms,which are frequently used in nonlinear bifurcation computing.With BE,a set of linear equations with power flow Jacobian or its transpose as coefficient matrix are to be solved in the solution procedure,and sparsity of power flow Jacobian can be exploited to enhance computational efficiency.Also,asymptotic numerical method（ANM） was used to determine the initial values for Newton iterations.Numerical examples in several power systems were presented to validate the method.