The precipitation of paraffin, which is hard to avoid, will cause a lot of damage during the whole oil-gas production segments, such as wellbore damaging, pipeline blocking, recovery ratio decreasing etc. So, this paper analyzed the effects after the precipitation of paraffin qualitatively and quantitatively. Using rock-capillary model to simulate the formation pore volume, and deducts the variation between paraffin precipitation and formation parameters using the correlation among surface area to volume ratio, porosity and permeability etc. We provide a theoretical foundation for oil-gas developing dynamic prediction after the precipitation of paraffin.