To analyze the efficiency of geometrical optics and its influencing factors on a Compound Parabolic Collector (CPC), a theoretical basis was provided for the optimization design and practical application of a linear Fresnel reflector system. According to the CPC characteristics of a linear Fresnel reflector system, a model was built using Matlab software; the geometrical optics efficiency was simulated by a ray-tracing method. The geometrical optics efficiency model was validated by TracePro software. The model was used to analyze the influence of outer diameter tolerance, position deviation of the absorber tube, and the profile error on the geometrical optics efficiency of the CPC. Results show that the mean geometrical optics efficiency of CPC with a gap of 32.5 mm, half-acceptance angle of 55°, truncation ratio of 0.3, and an absorber tube outer diameter of 70 mm, can be reduced rapidly when the outer diameter tolerance of the absorber tube is less than -0.4 mm, there is a horizontal offset, a positive vertical offset, or an increase in the profile of the CPC. In practical applications, the above factors should be avoided as much as possible or the range of the incidence angle of the CPC should be reduced in design to reduce the influence on its mean geometrical optics efficiency.