An optical film used for spectrum monitoring in facility agriculture is designed. Three kinds of optical films used in facility agricultural, red light filter, blue light filter, red and blue light filter are obtained by the combination of cut-off filters. Center wavelengths of red light and blue light are at 460 nm and 660 nm, respectively, and the transmission bandwidth is about 50 nm. The light transmission bands of red light and blue light are set according to demands of the plant to spectrum. In practical application, the center wavelength and bandwidth of light transmission can be set as needed. The filters can be used to make spectrum monitoring cells used in facility agriculture and agricultural research. The specific optical film is placed on the silicon photovoltaic chip, and light intensity of the optical panel preset band is monitored by measuring the power of the photovoltaic chip.