In this paper, we present a new Group Of Pictures (GOP) level bit allocation method for rate control of High Efficiency Video Coding (HEVC), which is the state-of-the-art video coding standard from ITU/ISO. Because of the difference of GOP coding structures between HEVC and H.264/AVC, the GOP level bit allocation method of H.264/AVC rate control is no longer adapted to HEVC. However, the existing rate control algorithms do not address it correctly. Thus, we propose a new GOP level bit allocation method which matches HEVC GOP coding structure exactly. Experimental results show that the proposed GOP level bit allocation method can achieve more accurate rate control, lower bit fluctuation, and slightly better Rate-Distortion (RD) performance than the original rate control algorithm in HEVC reference software HM-16.9 in both random access and low delay configurations without increasing encoding complexity.