The invention discloses a microwave heating device and an experimental method for true-triaxial hydraulic fracturing simulation experiments. The microwave heating device comprises a triaxial pressurizing unit, a microwave heating unit, a fracturing fluid injection unit, an acoustic emission monitoring unit, a temperature monitoring unit and a control and signal acquiring unit. Microwave heating equipment and hydraulic fracturing equipment are combined, change of properties of experimental test blocks due to missing simulated ground stress in a connecting process in existing experimental equipment is avoided, and influence of the property of thermal expansion and cold contraction of rock is simulated well; the situation of heated expansion of the experimental test blocks during microwave heating under the condition of simulated ground stress can be monitored; and the law of influence of parameters such as the ground stress condition, heating temperature, the test blocks, the temperature difference of the fracturing liquid and the perforation condition to cracking and extension of cracks can be inspected.