The invention discloses a method for manufacturing a high-performance airtight-level waveguide sealing window. The method comprises the following steps of 1, designing, customizing and processing parts; 2, cleaning parts; 3, carrying out nickel plating treatment on parts; 4, assembling parts by using an assembling tool; 5, integrally sintering parts; 6, carrying out air tightness inspection on modules; 7, carrying out gold plating treatment on the waveguide sealing window. The high-performance airtight-level waveguide sealing window manufactured by the manufacturing method has the advantages of wide working frequency band, small size, low loss, small standing wave, guaranteed air tightness, high reliability and the like. The waveguide sealing window can be widely applied to a microwave millimeter wave module, so that the airtight characteristics of the module are guaranteed. All functional bare chips in the module are prevented from being influenced by the external environment, and thereliability of the module is improved. The service life of the module is effectively prolonged.