Abstract: This paper focuses on the raycasting algorithm to the irregular data field and presents a new raycasting algorithm based on the space segmentation．By dividing the data space，an additional cube grid is added to the irregular data field and an octree is set up on this cube grid in order to implement the raycasting fastly．During the rendering stage，two methods have been adopted，including rendering the whole data field and rendering the isosurface of some part of data．The comparison of two methods is also discussed．