In a classic video encoder, Motion Estimation(ME) comes as a high computational complexity, about 60%-90% in a whole system. An efficient algorithm named as Hierarchical Full Search ME(HFSME) is proposed and implemented on the circuit. Based on AVS HD encoder, it supports the AVS variable block size match in which both B and P frames adopt two pictures as the reference frames, Rate Distortion Optimization(RDO) and four kinds of macro-block partition modes concurrently. It totally produces 18 motion vectors for each macro-block. Experimental results show that the architecture can achieve 30 fps under the conditions of two reference frames, 234×98 search range and 1 920?1 080 picture size. The algorithm & architecture proposed in this paper can meet the requirements of AVS HD Real-Time Encoder. The computational complexity of HFSME proposed in the paper is only a quarter of that of full search. At the same time, HFSME can provide the highest computational capability which is about 10 times higher than that of reference [12].