Abstract: An interactive method for prismatic grid generation based on surface boundary constraint is presented to solve the problem that it is hard to generate and modify prismatic grid in boundary layer in numerical simulation of fluid dynamics. First, the space advancing grid of surface boundary nodes is generated interactively in present method; second, the displacement of surface boundary nodes is calculated based on the thought that each layer of space advancing grid is acquired through motion of surface boundary nodes; third, the space advancing grid of surface interior nodes is generated by smoothly propagating the displacement of surface boundary nodes to surface interior nodes through the use of radial basis function interpolation; at last, the prismatic grid cells are created through establishing connections of all grid nodes. The present method is tested based on V-shape groove and airplane head, and some problems in the present method are discussed; the present method is also used to generate a prismatic/tetrahedral hybrid computational grid for a high respect ratio wing-body model; the hybrid computational grid is simulated on computational platform PHENGLEI;Results of test and numerical simulation both demonstrate that the present method can generate high-quality viscous prismatic grid.