The invention discloses a composite acid fracturing method for supporting the front edge of a fracture by utilizing a phase change material. The method includes the following steps that a prepad fracturing fluid is injected, a reservoir is fractured to form the hydraulic fracture, and meanwhile, the temperature of the reservoir is reduced to be the phase change temperature T of the reversed phasechange material or below; a mixed fluid of the liquid reversed phase change material and the fracturing fluid is injected, and part of the hydraulic fracture space is filled with the mixed fluid; an acid fluid is injected, the hydraulic fracture is etched, and the acid fluid further continues to flow into the deeper part of the reservoir; a displacement fluid is injected, so that all the acid fluid enters the hydraulic fracture; a well is continuously closed until the temperature of the reservoir is restored to be the phase change temperature T or above, the phase change material is changed into a solid state, and the front edge of the hydraulic fracture is supported; the well is opened, pressure relief is carried out, and the injected prepad fracturing fluid, a fracturing fluid, the acidfluid and the displacement fluid flow back. The injected fluids do not contain solid-phase particles, so that equipment abrasion is reduced; the reversed phase change material becomes liquid when injected, and after the reversed phase change material is heated and cured, the front edge of the fracture is effectively supported.