Greenhouse construction is light, the transmittance performance has a direct impact on indoor crops assimilates formation and indoor temperature level. Transmittance is an evaluation of greenhouse light transmission properties of the basic indicators, which refers to the percentage of the amount of light penetration into the greenhouse and outdoor sunlight amount. High transmittance, the light, the better the thermal performance of the greenhouse. Greenhouse transmittance by limiting greenhouse covering material translucent light transmission properties and greenhouse skeleton shadow rate of solar radiation in different seasons and with different heights, the transmittance of the greenhouse are subject to change.