Lateral micro-ion beam induced charge (IBIC) is a powerful method to characterize the electrical behavior of chemical vapor deposition (CVD) diamond thin film and further to evaluate its quality. In the process of IBIC data handling, a new model that the product of mobility and lifetime linearly increases from substrate side to growth side was proposed in order to separately analyze the carriers' contributions to charge collection efficiency. IBIC results shows that CVD diamond was primed by irradiation of 46 Gy proton dose with a 82.4% increase of average collection distance due to the space charge elimination inside the CVD diamond after irradiation.