Abstract: A fire fighting robot for urban environment is presented,and it uses articulated-chain-wheeled mobile style with differentially driven wheels,which adapts itself to climbing stairs and slopes.The constant overpressure achieved with real time leakage compensation inside the body endows the robot with explosion protection capability.When wireless signal is interrupted,it can return to a safe place automatically according to the sensory data memorized in the scouting process.Since position information from encoders has serious cumulative errors,a novel algorithm integrating data from encoders and ultrasonic sensors is built,which uses iterative closest point method to do data matching so as to adjust the position and orientation of the mobile robot.This algorithm realizes high accuracy in the process of automatic returning.