The track association problem of radar and electronic support measure (ESM) has been considered in the literature for several years.This problem is crucial for radar-to-ESM track fusion and is complicated by the presence of individual systematic errors and measurement errors.In order to improve the track association of radar and ESM sensors,a pseudo-linear filtering algorithm is proposed to estimate the target states and improve the stability of the filter.It is found that,however,the correct probability of radarto-ESM track association decreases as the radar measurement error decreases,when the pseudo-linear filter is used for ESM sensor filtering.In view of the strange phenomenon,this paper analyzes the reason for it by using the statistic theory and further performs Monte Carlo simulation to verify the analysis.