A new moving target tracking algorithm based on track-before-detect(TBD) is presented to detect and tracking moving target in IR image. The conventional tracking algorithm, Kalman filter and TBD, is inadequate to IR image. We investigate weakness of two conventional algorithm in IR image and newly propose improved tracking algorithm. The new method are based on TBD, and combines strength of conventional algorithm to overcome shortcomings. And we also propose vector quantization and updating vector quantization technique to overcome computation burden. Simulation result reveals the proposed algorithm has good performance in IR image.