Aiming at the threatening of the electronic reconnaissance and the attacking of the stealth target, the technique of the target detection based on L-band navigation signal is developed for passive radar. Passive radar has advantages over traditional radar on anti-stealth, survivability, anti-jamming capability, etc. The feasibility of the target detection is verified by analyzing the characteristics of the signal. The positioning accuracy of the 3D coordinate for the passive radar is analyzed based on Geometric Dilution Of Precision(GDOP). Theoretical analysis and simulation results validate the proposed technique.