Abstract: For more convenient measurement of antenna reflector, the measurement principle of forward intersection is introduced based on traditional method of theodolite steel-belt ruler. The new method forms a measurement system by two theodolites aligned in the center axis of antenna reflector. The light spot on the antenna reflector is formed by the coaxial laser beam of one laser theodolite, while the pitching angle is got by the other theodolite testing the spot. The deviation of the spot can be calculated by the measured value of the pitching angle, then realizing the measurement of the antenna reflector. The new method is simple and adaptable, and realizes contactless measurement of antenna reflector.