The invention realizes a measurement system for optical element transmittance and reflectance based on acousto-optic modulation, which is mainly used for solving the problem that the prior art is not high in measurement accuracy. The measurement system disclosed by the invention comprises a continuous laser, an optical path control chamber, an photoelectric amplification module, a feedback control module, a measurement rotary table and a parameter measurement module; the laser outputs laser with power to be stabilized; the laser outputted by the laser is radiated to a detector in a perpendicular manner after passing through the optical path control chamber to generate a current signal which is amplified by the photoelectric amplification module into a voltage signal; the feedback control module processes the voltage signal to obtain an feedback signal in order to control an acousto-optic demodulation driving device to adjust an acousto-optic demodulator to stabilize the laser power; the highly stable laser enters the optical member to be detected; and the laser power is obtained through measuring transmittance and reflectance of the optical member to be measured to calculate the reflectance and transmittance of the optical member to be measured. The invention is high in measurement accuracy and easy in operation.