Using the drilling, well logging, and all kinds of production data in different developing stages of the Tangjiahe oil field, this paper studies the changes of petrophysical properties of fluid units during the water flooding process, builds 3D fluid geologic models at different production times and gets a 4D geology model of the oil field. The 4D geology model is helpful in finding out distribution of residual oil, adjusting development plan, and improving ultimate production factor.