A plant effective growth specific wave band light detection device comprises a light sensor and a one-chip microcomputer connected with the light sensor; a probe position of the light sensor is provided with a filtering module comprising an upper filter sheet and a lower filter sheet with different wavelength photosensitivity; the upper filter sheet filters the part with wavelength higher than needed optical wave band, the lower filter filters the part with wavelength lower than the needed optical wave band, so the light sensor can obtain light intensity of the needed wave band. The detection device can realize real-time detection for plant photosynthesis effective specific wave band lighting intensity, and can save the data in a SD card for later analysis; the device also can send the data to a PC machine through a serial port for real-time processing or other operations; and the device is simple in whole circuit, strong in anti-interference property, good in stability, small in size, low in cost, high in precision, and is extensible.