Abstract: Using the improved G-expansion method，eighteen groups of exact solutions for Zakharov equation are constructed. As the result, the hyperbolic function solutions, trigonometric function solutions, and rational solutions with arbitrary parameters are obtained .When the arbitrary parameters in hyperbolic function solutions are taken as some special values, the solitary wave solutions can be obtained.When the arbitrary parameters in trigonometric function solutions are taken as some special values, the trigonometric function solutions can be expressed as periodic wave solutions. Experience has proved that application of improved G-expansion method can give some new exact solutions of the Zakharov equation, and increase the scope of the solution.This method has a very wide range of application to the study of nonlinear opticis and quantum optics .

Key words: nonlinear optics, quantum optics, the improved -expansion method, Zakharov equation , solitary wave solutions