<FONT face=Verdana>To a nonlinear control system

in order to utilize the useful couple between variables

and remove the harmful connection

the rules of harmonic control for nonlinear systems with disturbance compensation are given.According to the control rules

the state equation of harmonic control for nonlinear systems is established.Based on the equation

the full compensation condition eliminating extraneous disturbance

is given;and the state equation of nonlinear harmonic control systems

with full disturbance compensation

is obtained.By utilizing direct heuristic method

the any order approximate series solution of the equation can be obtained

this is a kind of useful approximate solving method of state equation for nonlinear systems.