This paper presents the design and implementation of a target tracking test bed based on wireless sensor network (WSN). The test bed is made up of a group of ultrasonic sensor nodes for ranging, a robot as mobile target for tracking and a laptop as base station for visualization. A new incremental optimization algorithm based on trilateration as well as a kind of changeable periodic scheduling scheme is applied in the test bed to pursue excellent tracking performance. The experimental result shows that the test bed can track a moving target effectively.Keywords-wireless sensor network, target tracking, sensor node, incremental optimization algorithm, scheduling scheme I.