Periodically inserted I-Frames will introduce periodical flickering artifact. For suppressing the flickering, a PI-method is proposed in this paper, in which the GOP length is enlarged and PI-frames are periodically inserted in each GOP. The PI-frames in PI-method are coded as both P-frames and I-frames, namely RP-frames and RI-frames respectively. The RP-frames will be decoded if there is no transmission error, and the RI-frames are in case of transmission error happening. The proposed method shows the frequency of flickering decreased to a low level with a small bit increment, therefore the objective visual quality improved as human eye is insensitive to low frequency of flickering.