Abstract: In order to obtain the luminous transmittance and haze of large transparent component in field, measurement scheme and method of calibration of system parameters based on double integrating spheres structure were presented. Furthermore the testing device was designed and manufactured. The optical path of device was adjusted by 6 dimensional mechanical adjustment structure firstly. Then the modulated directional light was generated by the illumination and collimation system based on LED source. Finally by using the detective part of double integrating spheres structure and the phase-locked amplifier technology, the signal was demodulated accordingly. The testing result shows that, by using the device, the absolute error of light transmittance is no more than 1% and that of haze is no more than 0.3%, which meet the precision requirement of engineering application. Moreover the repeatability of device was also good. The relative standard deviation of luminous transmittance and haze was 0.06 % and 0.05% respectively.