Device and method for online detection of water content of plant leaves

The invention discloses a device and a method for online detection of water content of plant leaves. The device comprises a detection box, a first electrode piece, a second electrode piece, a frequency measuring device and a computer, an SAM resonance detector and a stabilized-voltage power source are arranged in the detection box, the stabilized-voltage power source is electrically connected with a power source end of the SAM resonance detector, two detection ends of the SAM resonance detector are electrically connected with the first electrode piece and the second electrode piece respectively, an output end of the SAM resonance detector is electrically connected with an input end of the frequency measuring device, and an output end of the frequency measuring device is electrically connected with the computer. The method includes detecting a plant leaf to be detected by the SAM resonance detector, subjecting frequency of signals output by the SAM resonance detector to nonlinear random resonance processing to