Abstract: A grid generation quality test method according to 2D slicing and 3D slitting for 3D grids was proposed based on the idea of CT scan and its effectiveness was verified by the grid generation test examples. The test method was then used to examine the 3D Cartesian grid generation pre-processing software and the results indicated that the software has some abnormal empty grids inside the entities due to approximation of the entity by the facets. In addition, a method to eliminate these abnormal empty grids was also proposed.