Abstract: The effective recycling of waste printed circuit boards (WPCBs) can conserve resources and reduce environmental pollution. This study explores the pyrolysis and combustion characteristics of WPCBs in various atmospheres through thermogravimetric and Gaussian fitting analyses. Furthermore, this study analyses the pyrolysis products and combustion processes of WPCBs through thermogravimetric and Fourier transform infrared analyses (TG–FTIR) and thermogravimetry–mass spectrometry (TG–MS). Results show that the pyrolysis and combustion processes of WPCBs do not constitute a single reaction, but rather an overlap of multiple reactions. The pyrolysis and combustion process of WPCBs is divided into multiple reactions by Gaussian peak fitting. The kinetic parameters of each reaction are obtained by the Coats–Redfern method. In an argon atmosphere, pyrolysis consists of the overlap of the preliminary pyrolysis of epoxy resin, pyrolysis of small organic molecules, and pyrolysis of brominated flame retardants. The thermal decomposition process in the O₂ atmosphere is mainly divided into two reactions: brominated flame retardant combustion and epoxy combustion. This study provided the theoretical basis for pollution control, process optimization, and reactor design of WPCBs pyrolysis.