The invention aims to provide a positioning coded disc-based positioning method of an omni-directional mobile robot. A robot coordinate system XOY is built by taking a robot geometric center as an original point; three encoders are distributed on a positioning coded disc, wherein the included angle between every two adjacent positioning coded disc is 120 degrees; the axis of one encoder is positioned in the X positive direction of the robot coordinate system; transforming relationships between speeds of three driven omnidirectional wheels and velocity components of the robot coordinate system, as well as between speeds of three driven omnidirectional wheels and robot rotational angular velocities are determined; transformation of the coordinate system is performed; the relationships are combined to obtain the relationships between the velocity components Vx and Vy of a world coordinate system and the velocities of the three driven omnidirectional wheels of the robot positioning coded disc, as well as the relationships between the robot rotational angular velocities omega and the velocities of the three driven omnidirectional wheels; the Vx, the Vy and the omega are subjected to integration to determine the world coordinate and attitude angle of the omni-directional mobile robot. The method is the positioning method of the omni-directional mobile robot, wherein the three encoders are distributed on the positioning coded disc and the included angle between every two adjacent positioning coded disc is 120 degrees. A control system processes data fed back by the encoders through a positioning algorithm, and then the position of the robot can be positioned.