The invention discloses a method for experimentally determining the conductivity of an unpropped fracture in hydraulic fracturing of a shale reservoir, comprising: select an outcrop sample with a natural fracture in the shale reservoir, and cut the outcrop sample with along the extension direction of the natural fracture into no less than eight square rock slabs; use a laser scanner to obtain the rough topography data of the fracture surface of each square rock slab and calculate the area tortuosity; pick out the rock samples; model the rough surface of the selected rock samples; import the treated surface model into the engraving machine, and select the downhole core or outcrop rocks in the same horizon for repeated production; calculate the shear slippage at different positions of unpropped fracture according to the data of the shale reservoir; finally test the conductivity of the shale rock samples after shear slip.