Lapping of polycrystalline diamond compact (PDC) is a costly and time-consuming process that demands fundamental studies to improve its efficiency and quality. A series of experiments are conducted in this study to gain insights into the effects of the most influential factors on material removal rate (MRR). The well-known Prestons equation is found to be insufficient for a satisfactory prediction of MRR associated with PDC lapping, and a new model is developed. The current approach treats MRR as the product of removal intensity and removal density, which are formulated as simple functions of pressure, velocity and grain concentration. The newly derived model is in good accordance with the analyzed experimental results. The decrease in MRR at higher pressure and the connections between applied pressure, grain concentration and MRR can all be well explained by the proposed model.