As for the uncertainty of describing nonlinear seepage characteristics of low permeability reservoirs by fluid-solid coupling method, together with complex solving and difficult programming of fluid-solid coupling method, in order to depict stress sensibility and kick-offpressure gradient better existing in low permeability reservoirs catholically, this document started with nonlinear seepage physical simulation experiment for low permeability reservoirs in Daqing peripheral oilfields.The experiment results show that fluid seepage in low permeability reservoirs presents nonlinear seepage characteristics and start-up pressure gradient exists for sure while the permeability of liquid phase increased with pressure gradient.The higher the permeability is, the shorter the nonlinear seepage interval is in low permeability reservoirs and vice versa.Most developed regions in extra-low permeability formations lie in nonlinear seepage intervals.The above experiment results combining with practical formation and fluid parameters in Daqing peripheral oilfields and new method of kick-off pressure gradient treatment were applied to mechanism research of numerical simulation for certain block of Daqing peripheral low permeability sandstone reservoir.Four models were respectively established under the condition of considering stress sensibility and kick-off pressure gradient simultaneously(called composite model), or considering stress sensibility only(called SS model), or considering kick-off pressure gradient only(called KO model) or considering none of them(called conventional model).The development indexes such as formation pressure, daily production, cumulative production and recovery rate were calculated respectively under four models.The calculation results indicate start-up pressure gradient has a significant effect on recovery rate, therefore the recovery rate for conventional model is highest and reaches 17.53% while that of composite model is lowest, only 13.37%.In addition, the recovery rate for KO model is very close to that for composite model because the effect of stress sensibility on results are reduced due to adopting water flooding in early development stage and the influence of start-up pressure gradient becomes more obviously due to large producer spacing.Meanwhile, two infilling patterns suitable to the block by considering stress sensibility and kick-offpressure gradient simultaneously were compared and optimized.