Abstract: An approach based on sequential likelihood ratio test is presented to rapidly initiate track for dim moving target using the target amplitude acquired by the infrared tracking system. The two-dimensional dynamic assignment algorithm is adopted firstly to associate measurement with track, and the sequential likelihood ratio test is then taken to evaluate the quality of track. The target track is confirmed immediately once the likelihood ratio is greater than the threshold. This approach can take different scans to initiate target track according to the signal-to-noise ratio(SNR) of target, and the bigger the SNR of target is, the less frame it needs to achieve a given track detection probability. Some experiments are included and the results show that this approach can improve the speed of track initiation and enhance the detection probability of target track, without the limitation of the M/N logical method that the number of scans must be fixed to initiate target track with different SNRs.