The influence of internal loss and internal quantum efficiency on the output power of the laser is theoretically analyzed, and the comprehensive optimization design of the 852 nm Fabry-Perot (FP) laser is carried out by using PICS3D software. The designed device has the characteristics of small far-field divergence angle, low internal loss, and high internal quantum efficiency, which can achieve stable and high power output under large current. The basic transverse mode 852 nm FP laser was fabricated with internal loss less than 1 cm^-1, divergence angle of fast axis is 42.3°, divergence angle of slow axis is 5.6°, and unilateral output power of 115 mW without coating. The theoretical and experimental results show that while increasing the thickness of the waveguide layer and non-doping the waveguide can reduce the absorption of light caused by carriers and reduce the internal loss of the laser. By increasing the component of Al and the doping concentration in the AlGaAs material, the carrier leakage can be effectively suppressed and the high internal quantum efficiency can be ensured.