Abstract: The vertical development of micro joints,micro fissures and other macropores in Loess make it highly heterogeneous. In order to study the influence of the spatial heterogeneity on the dispersion capacity of loess medium,combined with the characteristics and advantages of indoor and field dispersion tests,two scale tests on the dispersion characteristics of loess medium were carried out at a test site in the hilly area of western Henan Province. The results show that:（1） The value of the dispersivity obtained by the radial convergent flow instantaneous injection method is stable,and the longitudinal dispersion coefficient representing the horizontal direction of the site has a good linear relationship with the average pore velocity；（2） The indoor soil column leaching test shows that the dispersion parameters of heterogeneous soil column is significantly larger than that of homogeneous soil column,and the difference reaches an order of magnitude. It is considered that the vertical development of micro joints,micro cracks and other macropores in Loess medium is an important reason for the larger vertical dispersion capacity of loess medium,and its influence on the vertical hydrodynamic dispersion coefficient of loess medium exceeds the degree of non-uniformity of pores and soil column height；（3） The combination of indoor and field dispersion tests has certain advantages in obtaining horizontal and vertical dispersion parameters of loess media.The comparison of test results show that the significant difference of spatial heterogeneity between horizontal and vertical direction of loess affects its hydrodynamic dispersion capacity,that is,the vertical dispersion capacity of loess is significantly greater than that of horizontal direction.