Ag-based photocatalysts have excellent photocatalytic properties, but their photocatalytic degradation performance is limited by the serious photocatalytic corrosion. In order to enhance the stability of photocatalytic degradation of Ag-based photocatalysts, here, the Ag2O/Ag2CO3 heterojunction was in-situ constructed and conveniently regulated by controlling the alkalinity of room temperature solid-state chemical reaction system. The photocatalytic degradation activity of the obtained heterojunction was influenced by the in-situ regulated component and band position of the Ag2O/Ag2CO3 heterojunction. The obtained optimal products AAC-6 displayed remarkable photocatalytic activity and high reusability. The apparent rate constant of AAC-6 is 20 times than that of Ag2CO3, it is also far higher than that of P25. The significantly enhanced photocatalytic performance can be ascribed to the matching energy position between Ag2CO3 and Ag2O, which can facilitate the visible light absorption ability and the efficient separation of photoinduced charges carriers. This study explored an in-situ one-step solid-state strategy to construct Ag2CO3-based heterojunction catalyst with outstanding photocatalytic performance, which may open a new perspective for the preparation of excellent photocatalytic degradation materials by solid-state chemical method.