Aiming at “Anti-Simulation Balloon Decoys for Nuclear Warheads”，which is one of the important countermeasures, some specific measures beneficial to penetration are proposed. By means of the thermal network model and difference method, the surface temperature distributions of spherical objects with different sizes in daytime and nighttime are calculated. The results show that in order to make the decoys usable both during the day and at night, a group of different sizes of decoys is designed so that the surface temperature of the decoys is distributed on both sides of the surface temperature of the balloon containing the warhead. This measure can undermine U.S. National Missile Defense (NMD) system′s ability to identify targets based on size and increase the complexity of identifying targets as well.