Common phenomenon of stress sensitivity in the tight reservoirs may result in great decline of production after producing for some time for the oil wells. According to the development problem of the tight reservoirs in WHZ oilfield，T2 testing method through core NMR was applied to obtain pore-throat radius and T2 cutoff value and other parameters. The microscopic characteristics of rock composition，the pore-throat structure and the distribution of porosity and permeability in the tight reservoirs of WHZ oilfield were analyzed. Based on the experiment of core flooding and the method of statistical analysis，the variation of core permeability with the confining pressure was understood，and the function relationship between dimensionless permeability and dimensionless confining pressure for the tight reservoirs was researched. Influencing factors on medium deformation for the tight reservoirs were analyzed and the oilfield production situation under various development modes was analyzed combined with the actual field situation. The result shows that the permeability damage of porous medium is irreversible under loading and unloading confining pressure for the tight reservoirs in WHZ oilfield，and the re-distribution of pore-throat structure may be affected in the process of pressure drop. It’s hard to recover the initial value and permanent damage may form for the reservoir even if energy is supplemented. Actual data of the WHZ oilfield show that the productivity loss may occur under pressure drop and the productivity with synchronous water flooding may be higher than that with no water flooding. Therefore，a reasonable formation pressure is necessary in the process of oilfield de? velopment，which may avoid production loss resulted from medium deformation of the reservoirs.