Tm:YAP crystal is one of the most important crystals for LD pumping 2 μm laser. The anisotropic structure of Tm:YAP produces anisotropic emission cross section. Tm:YAP crystals with different orientations have different output wavelengths and operating forms for different functions. Compared with the physical and chemical properties of Tm:YAG, the 795nm pump absorption band of Tm:YAP matches the emission wavelength of commonly used high-power AlGaAs diodes better. Tm:YAP has many advantages such as 4nm wider pump absorption bandwidth than that of Tm:YAG, higher efficiency, direct output of linearly polarized light.