Abstract: With the increment of scale of power system, in order to satisfy the increasing real-time and accuracy requirements of N-1 security verification, a real-time N-1 AC power flow calculation algorithm based on graphics processing unit-central processing unit（GPU-CPU） heterogeneous computing framework was proposed. In the algorithm, a method for solving the N-1 power flow problem was designed, which concatenated several independent power flow problems into one. The concatenated Jacobi matrix was generated by parallel processing, and the linear equations were solved by the direct method or the iterative method according to the scale of equations, in which the iterative method was parallelized. The algorithm was divided into CPU processing part and GPU processing part. CPU processed iterative initial value set, node admittance matrix formation, check set formation, iterative value correction and convergence judgement while GPU processed generation of concatenated Jacobi matrix. Correction equations solution was processed by CPU or GPU depended on the scale of equations, in order to achieve fast solution. The case analysis shows that, the proposed algorithm has high efficiency, high accuracy and small storage space. It has advantages compared with traditional N-1 power flow algorithm, which can meet the real-time requirement of N-1 power flow calculation and has engineering application value.