Abstract: In order to evaluate the practicability of the caudal fin thruster,SPC-Ⅲbiorobotic autonomous underwater vehicle(AUV) is taken as the research platform,the power and mobility of a caudal fin thruster and a screw propeller are compared under the condition of the same tonnage.The sea trial results about the power and mobility of the caudal fin thruster and the screw propeller show that the turning radius of the former is about 2/5 of that of the latter and the power consumption of the former is less about 7%than that of the latter at the speed of 2.2kn.Using caudal fin propulsion and carrying water quality multiprobes,SPC-Ⅲhas successfully performed a 49 km probe experiment and collected concentration distributing data of blue-green algae in the water of Taihu Lake.