Abstract: The present invention discloses a method comprising: A. acquiring the current I0 and I, and setting It1, It2, IR, Vmin, and Vmax. B. acquiring the speed V, and setting the speed VL and VH; C. a mowing motor runs in a low-speed mode, and a self-propelled motor runs at the speed VH; D. when encountering grassy areas, if I0<I<It1, keeping unchanged; if I?It1 and lasting for T1, skipping to E; if I=IR, skipping to G; E. the mowing motor switches to the high-speed mode; F. the mowing motor switches to the low-speed mode, V is switched to VH; G the mowing motor switches to the high-speed mode, V is adjusted to VL; H. the mowing motor stops, the self-propelled motors stop, then retreat and work along the original path, after attempting for M times, if the self-propelled motors stop again, bypassing and skipping to C to continue working.