The invention provides a method and device for measuring a harvested and cultivated target, and the method comprises the steps: determining a target object in an obtained target image and the actual position information of the target object based on the visual features of the target object; acquiring first point cloud data of the target object based on the actual position information and preset acquisition position information on the target object; based on the first point cloud data, determining a first tangent point position and a second tangent point position where the collection position is tangent to two opposite sides of the target object, a first length of a first connecting line between the first tangent point position and the collection position, a second length of a second connecting line between the second tangent point position and the collection position, and a first included angle between the first connecting line and the second connecting line; and based on the first length of the first connecting line, the second length of the second connecting line and the first included angle between the first connecting line and the second connecting line, determining the diameter at breast height of the target object at the collection position.