Abstract: Hydraulic fracturing is a significant stimulation technique to enhance hydrocarbon recovery from low-permeability reservoirs. The accurate prediction of breakdown pressure of fractured formations is a crucial step to make hydraulic fracturing success. Current calculation models of breakdown pressure are basically designed for homogeneous formations, and it has been a very complicated issue to predict breakdown pressure of fractured formations all the time. Affected by the intersection of natural fractures and perforations, three breakdown modes of hydraulic fractures may occur in perforated wells of fractured formations, namely breakdown along perforated rock bodies, shear breakdown and tension breakdown along natural fractures. Based on elasticity and lithomechanics theories and integrated with relation of natural fractures and perforations, we established a breakdown pressure calculation model for perforated wells in fractured formations by taking the above-mentioned three different breakdown modes into consideration. The calculation result shows that the established model can accurately calculate breakdown pressure of perforated wells in fractured formations and can also explain the extension mechanism of multi-fractures in areas adjacent to wellbore for perforated wells in fractured formations.