The invention provides a microwave remote sensing pixel element decomposing method based on land and water living beings classifying information, which comprises the steps of: by using land and water living beings classifying information of spectrum remote sensing data, establishing a microwave mixed pixel element decomposing module, and calculating component brightness temperature in a microwavemixed pixel element by solving an underdetermined equation set. Through obtaining positions and brightness temperature values of different components in the microwave mixing pixel element, the space resolution of the microwave mixing pixel element of water and land boundary is remarkably improved, microwave brightness temperature values and classifying information of the water and land living beings in an observing region are obtained, and the precision of post stage inversion of the microwave remote data is improved. The invention has the important meanings of completing the decomposition ofthe microwave mixing pixel element data of the water and land boundary in a global region, ensuring that the decomposed microwave remote data space resolution is similar to the spectrum remote sensing data space resolution adopted in the classification, solving the problem of low space resolution of the microwave remote sensing data, and broadening the application field of the microwave remote sensing data.