The non-linear analysis of chatter on-set process in single degree of freedom developed in the 1st report is further extended to chatter vibration with multiple mode coupling in actual engine lathes. The impulse excitation technique during actual turning is improved to obtain the non-linear variations of vibration parameters mi, ki, ci in each mode direction with applied load. The chatter on-set is then simulated by solving numerically the simultaneous vibration equation of mode coupling with taking both the variable mi, ki, ci obtained and the non-linearity of dynamic cutting process into account. The predicted stability thresholds of chatter vibration through the simulation are in good quantitative agreement with the experimental results which include the well known non-linear phenomena such as high feed and high speed stabilities of chatter and the finite amplitude chatter vibration.