Abstract: The S-block is a low-middle porosity and low-middle permeability reservoir.The steam stimulation pilot test shows that the steam stimulation technology is suitable for S-block.By using the numerical simulation method to optimize the steam huff and puff development mode and injection-production parameters,the study results show the development effect with the combination of vertical and horizontal wells is the best,the length of horizontal interval is 300 m,and the injection-production wells row spacing and vertical well spacing is both 100 m.The downhole steam dryness must be more than 40%,the steam injection rate is about 360 m3/d,vertical and horizontal wells' cyclic injection intensity is 60 t/m,10 t/m,the injection volume is 1 800 m3,3000 m3,the steam injection pressure is above 18 MPa,and the soak time is about 6 days.The study can provide reliable basis for the similar reservoirs in the optimization of development mode and injection-production parameters.