Obstacle detecting method for self-propelled mobile device

The invention relates to an obstacle detecting method for a self-propelled mobile device. Primarily, the mobile device is equipped with a detecting device on its front end. The detecting device is provided with a signal transmitting end and a signal receiving end. When an obstacle is detected by the detecting device, a sensing signal will be transmitted by the signal transmitting end, and the sensing signal reflexed due to the block of obstacles will be received by the signal receiving end. Then the mobile device can be controlled to change its direction automatically if the situation that the distance between the mobile device and the obstacle is too close is judged by the detecting device by means of the turning point of the reflexed sensing signal received by the signal receiving end. Accordingly, the location of the obstacle can be detected more accurately in case a misjudgment happens due to the different materials of the obstacle, so as to increase the practicability and efficiency for the whole impleme