The airborne active self-protect jamming becomes one of the most effective defense measures with the rapid development of EW (Electronic Warfare). The detection effectiveness and survivability of radars in the battle is seriously threatened. According to the demands for assessing the detection effectiveness of radar, detection probability is selected as a quantitative evaluation index. Firstly, via the organic combination of different modules resolved from the detection process of radar, the detection model is established and the mathematical models are recommended in detail. Then functional simulation of the radar detection process is devised, and the system based on HLA is realized. Lastly, detection probability with its target distance is obtained online through the simulation, and it is used for assessing the detection effectiveness of radar quantitatively. The result indicates that this model and method is feasible and effective, and it could provide some reference material for the research to radar counter-counter measures.