To improve the maneuvering target tracking precision under the clutter background at far distance, a maneuvering target tracking algorithm was proposed based on Unbiased Conversion and Unscented Transformation under the Earth Centered Earth Fixed (ECEF) coordinate system.The measured polar coordinate data of missile-borne radar was transformed into data under NED coordinate system, and then to ECEF coordinate system.The tracking was then implemented under ECEF coordinate system.In this method, the error caused by faraway nonlinear coordinate transformation was reduced by using Unbiased Conversion and Unscented Transformation.Maneuvering target tracking precision was further improved by using IMM algorithm.Simulation results show that the proposed method has higher tracking precision compared with the tracking under NED coordinate system.