Abstract: Sanjiang-Middle Amur basin spans the China-Russian boundary.The basin has a large area and has a good potential for oil and gas resources.Integrating well logging and seismic data, we conducted sedimentary study via core and outcrop description as well as, grain size analysis.The results show that the basin mainly develops fluvial facies, (fan) delta facies, lacustrine facies and sublacustrine facies, and marine facies sedimentary facies.On this basis, the sedimentary facies of the Veronican and Ortef-Apudi periods in the Early Cretaceous in the Sanjiang-Middle Amur basin were further studied.In the southwestern part of the basin (in China) included the Didao Formation, Chenzihe Formation, Muling Formation, and Dongshan Formation develop from the bottom to the top; while the Gorin Formation, Pionersk Formation, Pivansky Formation, Gornoprotoksky Formation and Strelnikovsky Formation develops from the bottom to the top of the basin (in Russia).This study not only provides a reference for further oil and gas exploration and deployment in the Sanjiang-Middle Amur basin, but also provides an important basis for the reunification of the Sanjiang basin in the eastern part of Heilongjiang province.