A selfdeveloped transmission system is introduced from three aspects: measuring principles, composition structure and calculation procedures. The white LED light source is used in this system, and its divergence angle is about 1 mrad. Variation of the light source is compensated by the integrating sphere, which can split the beam. The full facula is received by the aspherical mirror. The relative deviation between the transmission system and the nephelometer is less than 10% from the 2 km to 10 km. Influencing factors of measurement performance are analyzed from measuring principles and calculation procedures. The results show that the main factors affecting the measurement performance of the system are the accuracy of the standard, the linearity of measurement, and the stability of the system. At the same time, the assessment methods and the data of calibration accuracy, measurement linearity, and system stability are given, which verify the measurement performance of the system.