A method for soil moisture retrieval using multi-channel collaboration algorithm and passive microwave radiometry including: establishing mathematical relationship formula between brightness temperatures at any two channels according to microwave radiative transfer equation; collecting actual brightness temperatures of core channel and collaborative channels; selecting parameters to be retrieved including soil moisture value; giving a series of estimated values of parameters to be retrieved, calculating a series of predicted brightness temperatures of collaborative channels according to actual brightness temperature of core channel, microwave radiative transfer equation and mathematical relationship formula, comparing predicted brightness temperatures with actual brightness temperature, and determining soil moisture value.