Abstract: Allowing for factors affecting initial fracture pressure and breakdown pressure in hydraulic fracturing test, a hydraulic fracturing model was built by RFPA2D-Flow numerical simulation. The effect of pore water pressure coefficient, confining pressure ratio and heterogeneity on hydraulic fracturing was studied. The results showed that the changes of pore water pressure coefficient and confining pressure ratio have a remarkable effect on the initial fracture pressure and breakdown pressure during hydraulic fracturing process. The initial fracture pressure and breakdown pressure decrease with rising pore water pressure coefficient, and the largest drop could reach 37%. The initial fracture pressure and breakdown pressure decrease about 16% for the confining pressure ratio from 1.0 to 1.5. The investigation can provide meaningful guides for the design of hydraulic fracture engineering in practice.