Aim at the problem that the EO imaging tracking system is inconsistent with the model of probabilistic data association with amplitude information (PDAAI), which supposes that the greater the amplitude value is, the greater the probability of being the tracked target will be, a modified PDAAI (MPDAAI) is presented . Based on the fact that the amplitude and the motion of the interested target are consistent in a short period, the MPDAAI models the amplitude information and the motion information of the target as well as their consistency with Markov stationary signal to analyze the association procedure of motion and amplitude. The lower bounds of CramerRao estimation error for PDAAI and MPDAAI are calculated and discussed in detail. The theoretical analysis and experimental results show that estimating the target motion with the MPDAAI will be more accurate and more reliable than estimating with the original PDAAI.