Agricultural flexible chassis is a kind of vehicle with fourwheel independent steering and four wheel independent driving. There are four special motion modes of this chassis, including straight motion, cross motion, diagonal motion and inplace rotation. Each motion is achieved by controlling the steering stepper motor and the electromagnetic friction lock. For exploring the best controlling parameters of mode switching（MS）, a binary quadratic rotation combination test was conducted by using a selfmade flexible chassis test bench. The speed of the steering stepper motor and the locking voltage of the electromagnetic friction lock were selected as two factors in the test. The entropy method was then used to establish comprehensive evaluation index（CEI） for MS effect integrating the longitudinal force, lateral force, torque of chassis and the angle error of the offcentered arm. Analyses were presented about the influence of two factors on MS effect for the cross motion mode and the inplace rotation mode meanwhile. The regression equation of the CEI and the two factors was also established by DesignExpert 80. The optimal combinations of controlling parameters for these two modes were afterwards obtained by using response surface methodology and finally validated by experiments. The results showed that these two 〖JP3〗factors and their interactions had extremely significant influence on the CEI (P<0.01). The optimal combination of rotation speed and voltage for these two modes was 81r/min, 4.60V and 91r/min, 4.41V, respectively. The maximum relative error between the calculated and experimental values of the CEI was 4.73%. These conclusions can provide references for the study about motion control of agricultural electric chassis.