The invention provides an unmanned aerial vehicle carried object height measuring method, which comprises the steps of 1, carrying out initialization preparation; 2, controlling an unmanned aerial vehicle to take off beyond the safe distance away from the line; 3, observing data information returned by an image transmission system of the unmanned aerial vehicle in real time through a local displayin the process of controlling the height flight of the unmanned aerial vehicle, finding out the highest point of the object to be measured, and recording the flight height of the unmanned aerial vehicle at the highest point of the object to be measured; 4, elevating the height, finding out a reference object equal height point through the local display, and recording the flight height of the unmanned aerial vehicle at the reference object equal height point; and 5, calculating the height difference between the highest point of the object to be measured and the reference object equal height point. The advantages are that the device can work beyond the safe distance of the measured equipment, thereby avoiding safety accidents such as mistaken touch of live equipment; and the device can measure the height and height difference of high places which are not easy to climb and the height of objects in unreachable areas such as rivers and seas.