We find mode-locking steps in simulated force-velocity characteristics of exteal alteating-force(AF)driven colloids on a disordered substrate.Studies of mode-locking pattes in systems show that mode-locking steps are accompanied with the emergence of a dynamics phase:transverse solid phase.We also study the influence of temperature on the width of mode-locking steps.The mode-locked state is destroyed by thermal fluctuation and the width of mode-locking steps decreases rapidly with increasing temperature.In high velocity and low temperature regimes,due to the appearance of transverse solid phase and microscopically periodic velocity modulation,the step width changes little as temperature is varied.