The invention discloses an autonomous landform detection method and an unmanned aerial vehicle thereof. An airborne computer module, and a depth camera, an inertial sensor, a laser radar and an ultrasonic sensor and all electrically connected with the airborne computer module are included. Visual movement data acquired by the depth camera is fused with inertial data acquired by the inertial sensorto obtain odometer information, the flight distance and attitude are calculated and obtained according to the odometer information, surrounding environment contour data acquired by the laser radar isobtained and fused with the flight distance and attitude, a map is drawn, and obstacle avoidance data collected by the ultrasonic sensor is further fused to realized an obstacle avoidance function ofthe unmanned aerial vehicle. Thus, 3D environment information can be obtained in unknown environment without GPS, and autonomous navigation and map construction can be realized.