Abstract: In this paper, the passive and active L/S band sensor (PALS) data obtained during SMEX02, which consists of airborne L-and S-band radar and radiometer data, are used for the estimat ion of soil moisture.First ly, the multiple regression analysis is performed by combining the two channels, the most active and passive channel to retrieve soil moisture, but no effective improvement is achieved, which suggests that the multiple regression combining active and passive channels is not useful for the retrieval of soil moisture, a new method for soil moisture retrieval from large-scale C-band spaceborne radiometer is modified only to perform more efficiently, and the PALS data are used to prove the applicability of the method to high-resolution airborne radiometer and other band of the electromagnetic wave spectrum In addit ion, the evaluation of the method is conducted quant itatively.