Abstract: Aiming at the problem of inaccurate positioning of GPS signals when patrol robots work in campus environment, which are easily blocked by trees and high buildings, a combined positioning method of GPS and ODO is proposed. This method takes GPS coordinate information as initial position, odometer information as main navigation, pulse signal of GPS receiver as real-time correction data, using Kalman filter algorithm to optimize the state estimation of the system, obtaining more accurate state estimation value, and finally uses state estimation value to correct the navigation error of the system. At the same time, validation and simulation are carried out on the experimental platform. The experimental results show that the trajectory error of the robot can be controlled within 5 cm after it travels at 150 cm/s speed for 80 seconds. It is concluded that the positioning accuracy and reliability of the robot can be improved by using multi-sensor fusion technology. That is to say, the positioning method combined with GPS and ODO can effectively improve the positioning accuracy and reliability of the robot.