Vegetation cover is one of the most important ecosystem on land surface. The vegetation cover protects land surface from desertification and is a food source for human and animals. The vegetation biomass is an important parameter as it presents the green and developing state of the vegetation cover that influences to the ecosystem. This paper introduces some preliminary research and experimental results carried out by scientists of the Space Technology Institute, Vietnamese Academy of Science and Technology using passive microwave remote sensing forestimation of agricultural crop biomass.