Abstract: To render rectilinear grid quickly to produce high quality image,this paper gives B-spline hybrid filtering and implementation speed grid that are applied to GPU-raycasting for rectilinear grid.Proposition about sign property of derivative of B-spline basics is proved.Furthermore,it is shown that there are significant errors in some cases when S&H method is used to compute derivative of B-spline.According to such a conclusion,in ray integration,S&H method is used if the condition is satisfied;otherwise B-spline basic equation is used.Moreover,proposition about range of derivatives of B-spline functions is proved,so that gradient magnitude modulation and speed grid are implemented in GPU;in ray integration,interfaces between materials are shown with gradient magnitude modulation and empty space is skipped with speed grid.As a result,GPU-raycasting with the hybrid method in this paper frees artifacts caused by generalized S&H algorithm;it is faster than stationary step GPU-raycasting based on B-spline basic equation;it can represent the true feature of things measured or simulated if they are smooth.