The invention discloses a production process for a transmission gear box. The process comprises the following steps that a, charging, punching and edge deburring are integrally conducted, and a first semi-finished product is obtained; b, stamping and flanging are conducted, and a second semi-finished product is obtained; c, a gear shaft is embedded; d, the perpendicularity of the gear shaft is adjusted; e, the required length of a riveting part is calculated through a control module, and the control module controls a cutting die to remove the surplus riveting part; and f, the gear shaft is riveted, a riveting die rotates and stamps the riveting part, the riveting part is flattened, and a third semi-finished product is obtained. Charging, punching, deburring and integral stamping are completed, and steps are simplified; the machining precision of riveting of the gear shaft is improved; and the riveting part of the gear shaft does not protrude from the surface of the gear box, finishing does not need to be conducted, and the riveting strength is high.