To conduct better hydraulic fracture design and execution in conglomerate formation, this paper focuses on irregular fracture and pressure fluctuation when the hydraulic fracturing was conducted. The conglomerate was simplified as compound medium which is consisted of three mechanically different parts depending on critical energy release rate, fracture expands or stops. Based on fracture mechanism and coordinate transform, the energy release rate of virtual fracture at the tip of hydraulic fracture is derived, and then the best way for expansion is assigned. The critical fracture pressure is deducted from energy release rate and critical energy release rate.The simulation on morphology characteristics with different size, content, intensity gravels agree accords well with experimental results.Results show that the size and content of gravel, intensity of each part are significant influencing factors for characteristics and pressure fluctuation.