In the process of focused ion beam induced deposition (FIBID), the distribution of precursor gas adsorbed on the surface of structure and interaction of incident ions are the main elements to control the fabrication of 3D micro/nano structures. In order to get the optimal fabrication parameters, the model of FIBID fabrication needs to be clarified. To this end, this paper presents a Continuous Cellular Automaton (CCA) approach to simulate the deposition process induced by focused ion beam. By using the gas distribution obtained from Precursor Gas Distribution Calculating Model (PGDCM) and considering the incident ions as the Gaussian distribution, the proposed method performs as an effective tool to capture the profile of deposited structure in fabrication process and determine the final profile. Sputtering and etching are also taken into consideration to get a more accurate net deposition velocity. Pillars are fabricated to verify the simulation results. Pillars height and diameter are measured as criterion for simulation results.