In order to scientifically evaluate the protection ability of the laser angle deception interference system, it is necessary to consider the important link of laser warning to guide the interference. Firstly, according to the principle of scattering detection, the warning model of laser scattering warning device with six windows was established. Secondly, according to the relationship between the attack direction of laser-guided weapons and the direction of laser indication, as well as the protection ability of diffuse reflectors, a calculation model of protection coverage under warning guidance was established. On this basis, the results of warning orientation were analyzed, and the protection ability of laser deception interference system guided by warning was evaluated. The results show that when the warning-guided interference laser irradiates three fixed diffuse reflectors with uniform distribution, the protection coverage is 78.1%. If the direction of the diffuse reflector can be adjusted according to the warning results, only one diffuse reflector will be used, and the protection coverage can also be increased to 98.2%. This study can provide a theoretical basis for the use and evaluation of protection ability of laser angle deception interference system.