According to the structure of remotely operated vehicle (ROV),the mathematical model of propeller space layout and final thrust was established.The above model was used to study the influence of the installation position and installation angle of horizontal thruster on the three motions of surge,sway and yaw.The installation angle of the horizontal thruster on the small ROV was determined according to the specific working environment.Under the condition that the thruster installation angle was determined,a method of horizontal thruster thrust distribution combining power normalization and sequence quadratic program(SQP) algorithm was proposed.This method has been proved by the simulation to the rationality and validity of the thrust allocation.