For the sake of improving jamming efficiency of band-limited Gaussian noise to GPS military signals, this paper use code tracking error of GPS receiver as the jamming effect evaluation index to optimize band-limited Gaussian noise jamming frequency offset and bandwidth under given JSR. On the basis of analysis GPS P(Y) code and M code signal power spectrum characteristics, according to operating principle of non-coherent early-minus-late power DLL, the expression between jamming frequency offset and bandwidth with code tracking error is obtained through theoretical derivation. Based on practical condition to set the DLL parameters of receiver, the efficient band-limited Gaussian noise jamming frequency offset and bandwidth to P(Y) code and M code signal is simulated and calculated quantitatively under the different JSR respectively. Taking the minimum JSR of causing DLL lock-lose as primary opting criterion, at the same time to consider the influence of jamming implement complexity and frequency domain filtering, the conclusion of comprehensive compare show that when the JSR within 50~60 dB, the jamming frequency offset and bandwidth to P(Y) code is set to 0 and 8.8 MHz respectively, the jamming frequency offset to M code of BOCsin and BOCcos modulation is set to 9.833 MHz and 10.9 MHz respectively, the jamming bandwidth is set to uniform 10 MHz.