Enhancement of heat transfer rate of a heat surface in a three-dimensional channel flow with insertion of a moving slender block is investigated numerically. A slender block is installed along the direction of the channel flow, and the movement of the slender block is in periodic motion and transverse to the channel flow. Due to the interaction between the channel flow and slender block moving, a large circulation vertical to the channel flow is induced and follows the moving slender block closely. The behaviors of the slender block and circulation destroy and suppress the velocity and thermal boundary layers on the heat surface periodically. These phenomena first observed cause the heat transfer rate of the heat surface to be enhanced especially in the downstream of the heat surface. The maximum magnitude of enhancement in this study is about 50%. (C) 2010 Elsevier Ltd. All rights reserved.