The solid-core polarization-maintaining photonic crystal fiber is very suitable for the application of the fiber optic gyro because of its unique advantages in birefringence, temperature, and radiation resistance. However, the loss is large, which affects the improvement of the performance of the photonic crystal fiber gyro. The scattering caused by the surface roughness of the air hole inner wall is one of the causes of the loss. For the scattering loss of the solid-core polarization-maintaining photonic crystal fiber, a fiber scattering model is established, and the simulation result of the scattering loss is 0.179 dB/km. A fully automatic test device is built with a measurement sensitivity of 1 pW, a scattering angle measurement range of 15° to 165°, and a fiber rotation angle resolution of 1°,the measurement of a three-dimensional scattering ball is realized. And the measured scattering loss of the fiber is 0.23 dB/km, which is in agreement with the theoretical simulation result.