In order to improve the beamforming robustness of microphone array with mismatch errors in actual environment,a robust frequency invariant beamforming algorithm is proposed based on linear constrained minimum variance diagonal loading method.In this proposed algorithm,the spatial response variation function is incorporated with linear constrained minimum variance beamforming algorithm,and the two norm of the weight vector of beamformer is constrainted into inequality,then the analytical solution and global optimal solution for the weight vector can be solved by using Lagrange multiplier method and CVX iterative,which can improve the robustness of frequency invariant beampattern,as well solve the mismatch error caused by uncertainty in microphone gain,phase or position.Simulation results illustrate that Lagrange multiplier method of the proposed algorithm outperform CVX iterative solution in improving the robustness of frequency invariant beamformer.