This paper, based on a large amount of studies on proportional navigation laws, address a pursuit-guidance method for a modern fighter,in which the PPN (Pure Proportional Navigation) is used to pursuit an air adversary which may evade in different modes. Simulations demonstrate that the proposed law can be effectively used to pursuit or intercept maneuvering targets. It is expected that this paper will be helpful to the design of pursuit- guidance system for modern fighter.