Abstract: Putaohua oil horizon with a medium-low permeability in Taipingtun oilfield will be reduced in permeability after the performance of all measures of yield increase and augmented injection from drilling to injection,and thus decreasing the recovery ratio.The laboratory test on oil and gas horizon damage is of the purpose to measure the permeability varia- tion of the reservoir before and after the contact with foreign working fluid through the evaluations of velocity sensibility, water sensibility,acid sensibility and salt sensibility,and further to evaluate the sensibility degree of reservoir and to analyze the mechanism of reservoir damage.On the basis of laboratory tests,evaluated are the oil horizon damages in the processes of drilling,perforation,fracturing,acidification, and water injection.Corresponding countermeasures of res- ervoir protection are carried out to decrease the damage on reservoir during all kinds of performances and to enhance the production capability of low-permeability reservoir.