A reflectivity measurement method capable of causing laser amplifier front laser emission is disclosed. The method is characterized by using a wedge mirror to realize single surface reflection; usingan off-axis parabolic mirror, a plane mirror, an attenuation sheet, CCD, a small aperture diaphragm and a visible light source to realize angle measurement of wedge mirror placement; combining a laserpower meter to measure reflectivity of the wedge mirror; through changing attenuation multiplying power of the attenuation sheet, testing laser amplifier output power corresponding to the different attenuation multiplying power; through external-extension curve, acquiring an attenuation multiplying power threshold capable of causing laser amplifier front laser emission; and combining the wedge mirror reflectivity acquired through measurement to determine the reflectivity causing the laser amplifier front laser emission under the angle. In the invention, the reflectivity of the laser amplifierfront laser emission is effectively measured, confirmation confidence of the reflectivity causing the laser amplifier front laser emission is increased and operation is simple.