Airborne early warning radar towing infrared search and tracking system for detection is a kind of important working mode of multisensors coordination on the same platform. In order to try to find out about the quantitatively evaluative patterns influence on the IRST's detective efficiency, taking the detecting probability of the IRST as an evaluation criteria, this paper establishes a mathematic model of the successful towing probability under condition of multiinstantaneous field of views, calculates the view zones searched to meet the needs of a certain successful towing probability under condition of the different radar working modes, and then derives the relationship formulas among the detection probabilities, the operating distances, and the pulse accumulations. Under the premise of ensuring that the successful towing probability is 0.99, the radar in high precision measurement mode can acquire the best towing effect to make the search area of IRST reduce to 1/180 of the original, the time saving efficiency is 99.4%, and the process of target capture accelerates. The saved time can use to accumulate pulses, the detective probability corresponding to the maximum action distance increases from 0.5 to 0.985 3 when the accumulated number of pulses reaches two pulses, thus significantly improving the detective efficiency of IRST.