Considering the infrared guidance munitions need the information of time-to-go, when using impact angular constraint guidance law, one kind of switched-gain proportional navigation guidance(SGPNG), without time-to-go for it′s input, was proposed. Based on the analytical relationships among the middle-terminal navigation ratio, acceleration constraint and field-of-view constraint when desired terminal impact angle was fixed, the calculation model of navigation gain was established. Then the navigation gain and the location of switched-gain were got. After that, the SGPNG performance was compared with that of trajectory shaping guidance(TSG). Simulation results and the engineering application analysis show that the SGPNG achieves the goal of desired impact angle, location, the field-of-view angle limit and acceleration constraint. Compard with the TSG, the SGPNG needs less hardware resources.