Abstract: Double-star positioning system has its disadvantages because the mode of the system is active two-way ranging, such as user's position is easily exposed to enemies, the time delay, and so on. So passive ranging mode is considered to improve the double-star positioning system. Two improved schemes with adding pseudo-satellite based on the actuality to get more observed quantities are presented in this paper and optimum layout of the pseudo-satellites is also pointed out. When the position of pseudo-satellites is in optimum condition, it can be proved that the way that adding pseudo-satellites in the double-star positioning system can really improve the precision of position by comparison and analysis.