One fast inter mode decision algorithm is proposed in this paper. The whole algorithm is convoluted with block matching process. Firstly, beforeME process, by exploiting spatial and temporal information, a skip mode early detection algorithm is proposed. Also, in this stage, edge gradient is used to filter out unpromising modes. Secondly, during the ME stage, the original search window is separated into several layers and our fast decision scheme works with motion information of each layer. Moreover, before stepping into small modes, the distribution of SAD (sum-of-absolute-difference) and RD (rate distortion) costs of big modes are analyzed in an early stage to accelerate the inter mode decision process. Experiments show that our algorithm can achieve a speed-up factor of up to 66.0% with trivial bit increment and quality degradation.