Abstract: Using jamming efficient carrier-to-noise ratio and code tracking error as the jamming effect evaluation index, the influence degree of current GPS and Galileo navigation signals suffered from single frequency, band-limited Gaussian noise and matching spectrum jamming is researched respectively by theoretical derivation and simulation analysis. The inner relationship among signal modulation mode, receiver parameters set and enhanced anti-jamming performance is obtained. Comparing the signal systems of Beidou Navigation Satellite System (BDS) with GPS and Galileo, we achieve the following suggestions for enhancing anti-jamming performance: B1-C of BDS can be optimized to the modulation combination of CBOC(6,1,1/11); B2 can be designed TD-AltBOC(15,10) modulation with the same pseudo random modulation sequence of pilot channel; and B1-A and B3-A could employ the signal modulated by TDDM-BOC_c(15,2.5) and BOCc(15,2.5).