Abstract: By assembling Kinect camera and 2D lidar, this paper proposes a low-cost obstacle detection method for mobile robot. The correspondence between depth image points and laser radar ranging points is constructed based on joint calibration of the Kinect camera and lidar. The location of environmental obstacles is computed from the detection datum of these two sensors. There are three steps for the computations:1) Kinect camera and 2D lidar obtain the depth image and 2D laser points respectively; 2) the depth image is transferred into virtual laser points; 3) according to the correspondence, the obstacles location is calculated from the integration of virtual laser points and 2D laser points. The experiments show this method is proper and effective, and the computations results could be used to determine the obstacles for mobile robot.