In order to implement high-precision and rapid passive locating of airborne IRSTand considering the limit of ordinary inter-flight data link to large-capacity image transmissiona method for passive locating of airborne IRST was proposed based on laser link.The principle of locatingthe process of establishing airborne laser linkthe infrared image registration and fusionand the infrared target detecting and recognition were analyzed.Unscented Kalman Filter (UKF) was studied and was used to estimate the state parameters of the target taking the effect of observation equations nonlinearity and noise into consideration.The simulation result showed that the method can improve the evaluation accuracy of distance and velocityand can also improve the locating precision with increased airborne IRST sampling frequency.