The semi stable limit cycles and bifurcations of Liénard equation are studied by the perturbation incremental method. Firstly

a perturbation method is used to obtain an initial solution for the case λ≈0 by using a nonlinear time transform and rewriting the differential equation as an integral aqelation. Secondly

because the new solution scheme is based on an incremental approach

the parameter λ can take arbitrary values. Finally

a practical example is given to show the efficiency of the method