During wafer rotation grinding, the wafer is centered on a porous ceramic vacuum chuck and so; the dressing shape of vacuum chuck becomes a critical factor affecting the flatness of ground wafers. In this paper, a theoretical model of the dressing shape of vacuum chuck in wafer rotation grinding is developed. From the model, the relationship between the dressing shape and the affecting factors is given. The dressing shape is predicted by computer simulations based on theoretic model and the vacuum chuck dressing experiments are conducted to verify the theoretical model. It is shown that the theoretical analysis matches the experimental measuring results very well. The study results provide a theoretical basis for analysis of the relationship between the dressing shape and the flatness of ground wafer, for improving the flatness of ground wafer and for selecting the proper parameters of grinding process.