The invention provides a plant population photosynthetic rate measuring apparatus and method. The plant population photosynthetic rate measuring apparatus comprises a cuboid organic transparent glass framework and five independent organic transparent glass plates; the five independent organic transparent glass plates are installed on an upper surface, a left surface, a right surface, a front surface and a rear surface of the cuboid organic transparent glass framework in a detachable manner; and the cuboid organic transparent glass framework comprises four upright posts, and one upright post is successively and uniformly provided with five CO2 glass analyzers from top to bottom. The plant population photosynthetic rate measuring apparatus can accurately measure a photosynthetic rate of a plant population.