A general method of modifying function projective synchronization of a class of chaotic systems is proposed in this paper by designing a suitable response system. The two schemes of obtaining the response system from chaotic system are established based on unidirectional coupled synchronization. Since chaos synchronization can be achieved by transmitting only a single variable from driving system to response system, this method is more practical. The stability analysis in the paper is proved using Lyapunov stability theory. Numerical simulations of a hyperchaotic system verify the effectiveness of the proposed method.