In many studies about land surface parameters inversion using the zeroth order model

the equivalent scattering albedo are usually set to a small value（0.05—0.1） or to zero

which lacks of experimental data support.In this study

the equivalent scattering albedo for cotton and soybean in different growing stages are estimated based on the observations from the Truck-mounted Multi-frequency Microwave Radiometer using the least squares technique.Further investigations are also made to investigate the variation of equivalent scattering albedo versus frequency

observation angle and the crop phenology.The result can provide some theoretical reference for determining the equivalent scattering albedo of vegetation using the zeroth order model to inverse land surface parameters.