The invention discloses a land surface plant canopies ecological water content remote sensing retrieval method based on spectral analysis. The method comprises the following steps: (1) actually measuring plant canopies spectrum data and biochemical data, wherein the biochemical data comprises fresh weight, dry weight and leaf area; (2) preprocessing the actually measured spectrum data and performing spectrum feature extraction; performing moisture noise removing, spectrum differential computation and envelope line removing; (3) computing and extracting the required plant index according to theactually measured reflecting spectrum feature; (4) preforming correlation analysis on the plant field actually measured spectrum data and the biochemical data, and establishing the model of the computed plant index and the plant water content; and (5) analyzing the remote-sensing image spectrum feature, and realizing the plant canopies ecological water remote-sensing quantitative retrieval by combining the plant water content model established through the actually measured data. By utilizing the method disclosed by the invention, the dynamic monitoring on the plant canopies ecological water content can be realized, and the monitoring accuracy is high.