Special tools were designed according to the irregular geometry of the blade profile when aero-engine gas turbine blades were machined, and problems such as frequent conversion of machining datum, low machining quality and low production efficiency existed. In this paper, a low melting point alloy casting method was used to reconstruct the machining benchmark, and the metal mold casting process was studied experimentally. The results show that the machining benchmark of the gas turbine blade produced by the metal mold casting process can meet the hardness requirements of workpiece clamping. The rapid separation between the workpiece and benchmark block could be realized by mechanical crushing, hence the process could shorten the manufacturing cycle and improve the production efficiency.