Post-weld heat treatment (PWHT) is expected to release the welding residual stress (WRS) of deck-rib double-side welded joints in orthotropic steel decks (OSDs). In this paper, the WRS distribution of deck-rib double-side welded joints before and after PWHT is evaluated by hole drilling method and numerical simulation, and the effect of PWHT parameters on WRS relaxation is further compared, and reasonable parameters are suggested. Based on the principle of WRS relaxation by PWHT, the feasibility of secondary continuous PWHT was explored. The results show that PWHT can effectively release the WRS and make the distribution more uniform. Extending the heat preservation time and increasing the temperature can release more WRS, and the heating and cooling rate has little influence on the WRS, so it is recommended to use the specified maximum value. The effect of secondary continuous PWHT is slight, and it is not recommended for use.