Abstract: In order to achieve complex task allocation dynamically and effectively in multi-robot systems,a general formal description method is presented.The proposed method defines both robot and task capability vectors from the viewpoint of capability classification,and formally describes the multi-robot task allocation problem.Task accomplishment conditions are discussed for both single and multiple robots.Based on this formal description method,a novel market-based wholly distri-buted multi-robot task allocation method is proposed.Simulation results show that this method can achieve complex task(allocation) effectively and dynamically in multi-robot systems in a wholly distributed way.