A special pulse Nd:YAG/Cr:YAG laser is designed. A particular output mirror consists of a polarization coupled mirror and a terbium scandium aluminum garnet (TSAG) crystal. Using the Faraday magneto-optic effect in the TSAG crystal and a high reflectance mirror, the characteristic of the pulse laser can be actively modulated by adjusting the magnetic intensity. An optimal magnetic intensity (5090 Gs) is measured for output power, pulse energy, peak power, and pulse width. This provides a modern and special reference for the design and manufacture of pulse lasers.