An algorithmic method of calculating angle precision of remote target by dual-aircraft coordination passive locating way is performed. Firstly, with some proper hypotheses, an analytic equation of dual-aircraft coordination locating remote target based on Direction of Arrival (DOA) is set up. Then the mathematic relationship between azimuth angle and Time Difference of Arrival (TDOA) based on wavepath difference is established. And then, by using the method of Taylor Series, an approximate algorithm of calculating the azimuth angle's probability distribution by calculating TDOA's probability distribution is presented. Finally, the affection of different dual-aircraft's position on angle precision is analyzed through simulation. The feasibility and the validity of the algorithmic method are demonstrated by the experiment.