An efficient intra prediction method was proposed to decrease the complexity of the video coding of new generation system. Some technologies used in the new generation standard of video coding (High Efficiency Video Coding, HEVC) were introduced, such as angular prediction modes, planar prediction mode, LM prediction mode and the Rate Distortion Optimization(RDO) method for selection of an optimum mode. Firstly, the Sum of Absolute Difference (SAD) was taken as a cost function to process residual errors to obtain optimal RDO initial candidate modes. Then, a simplified rate-distortion cost mode and a Most possible Prediction Mode(MPM) were used to obtain the RDO candidate mode, and the RDO was used to achieve the optimal mode with the least bit rate. Finally, the improved method was verified on the HM 4.0 platform of the HEVC measuring model. Extensive simulation results demonstrate that the proposed method is quite efficient for intra mode prediction speed-up. Compared with the method in HM 4.0, the proposed algorithm reduces the encoding time by 30.18% while the Peak Signal-to Noise Ratio(PSNR) remains almost the same (average reduce 0.06 dB). The bitrate is only reduced by 1.97% on average. Compared with the method in reference <参考文献原文>, the complexity and the bitrate are reduced by 11.45% and 0.46% respectively, and the PSNR increases by 0.01 dB.