This paper reviewed the recent advance in the bulk transfer coefficients over the land, from its research course, computing methods and characteristics of space and time variations as well as relations with some surface factors and so on. On the basis of comprehensive understanding of its present situations, the authors discussed some key scientific problems in this field. Firstly, some difficult problems required to be solved，such as the land surface parameters′ calculation and observation over inhomogeneous land surface and development similarity theory which can be applicable to the inhomogeneous land surface. Secondly, studies of the bulk transfer coefficients over humid regions of China must be strengthened. Thirdly, whether or not understanding the landatmosphere interaction process over inhomogeneous and complicated land surface in its entirety, the land surface parameters′ expandedness form local to regional scope is a critical and difficult problem. Finally，the feasible method of using satellite remote sensing and field observation data to estimate the land surface parameters and flux densities over the inhomogeneous land surface was discussed.