Abstract: Formation damage research is very important to the development of low permeability reservoirs. Formation damage in recovery process of A-Nan low permeability sandstone reservoir is thoroughly studied on base of analysis of production performance and cores. The main factors leading to formation damage include paraffin precipitation lowering the permeability of the nearwell - bore formations in producers, poor quality of injected water resulting in near wellbore formation damage in injectors, particle movement leading to deep formation damage, germ plugging and formation sensitivity damage. These study results can provide a reliable basis for unplugging measure sellection and formation damage prevention in recovery process in A-Nan oilfield.