With the quad-tree based coding structure and more flexible intra-modes, the coding efficiency provided by intra-technique in inter-frames of HEVC is much higher than the preceding standard H.264/AVC. However, the computing complexity is also significantly increased. Although only a few CUs are encoded as intra-mode in inter-frames finally, almost all CUs need to be checked all the intra-options to obtain the optimal mode, which may be in fact unnecessary. Unlike most existing fast algorithms, which focus on accelerating intra-prediction itself, we propose a novel feature to quantitatively estimate the possibilities of doing intra-prediction for CUs. Based on this feature, we further design a fast intra-prediction decision algorithm to determine whether a CU needs to be checked the intra-prediction. The experimental results show that our algorithm can reduce more than 60% computing resources with a negligible loss in rate-distortion performance for intra-module in all inter-frames. Besides, our method can be compatible with all other existing fast algorithms.