The invention discloses a standing tree height measuring method based on monocular vision. The problems that existing tree height measurement has complex operation and large consumed time and the standing tree height cannot be rapidly and conveniently detected are solved. The method comprises the following steps of calibrating a camera, acquiring internal parameters of the camera, performing standing tree contour extraction on an input image, establishing a geometric model of the distance between an image coordinate system and a world coordinate system, acquiring a standing tree image depth relational expression, establishing a height pixel coordinate mapping model, acquiring a to-be-measured target height relational expression, and calculating a standing tree height according to the shooting height and angle of the camera. The method has low measurement cost and high working efficiency, only an existing smart phone needs to be adopted, only the shooting angle and the shooting height need to be obtained, and operation is more convenient and faster. Moreover, the measurement method does not need complex operation, less time is consumed, the algorithm precision is high, the automation degree is high, and the operation is simple.