The invention provides an assembly process of adie assembly. The assembly process comprises the following steps of S1, assembling, namely assembling a cathode assembly, assembling an anode assembly and assembling an exhaust pipe assembly; S2, assembling the die assembly, namely assembling the assembled cathode assembly, anode assembly and exhaust pipe assembly together to form the die assembly; and S3, assembling the die assembly and other assemblies to obtain a magnetron finished product, wherein the assembly of the die assembly comprises pressing a magnetic pole K side, connecting the anodeassembly and the magnetic pole K side and then pressing; pressing the cathode, and assembling the cathode assembly and the anode assembly together; after the cathode is pressing, assembling the anodeassembly and the exhaust pipe assembly together to form the die assembly, and welding overall; carrying out leak detection and exhaust operations on the die assembly, removing an oxide layer of the anode assembly, and installing an antenna cap; deburring and aging. The assembled die assembly has the advantages of no damage to each component, high yield, no crack, no leakage hole, and tight weldingbetween the assemblies.