The bedrock weathered crust in front of the Altun Mountains in the Qaidam Basin, western China, is different from others because this is a salt-lake basin, where saline water fluid infiltrates and is deposited in the overlying strata. A large amount of gypsum infills the bedrock weathered crust, and this has changed the pore structure. Using core observation, polarized light microscopy, electron probe, physical property analysis and field emission scanning electron microscopy experiments, the characteristics of the weathered bedrock have been studied. There are cracks and a small number of dissolved pores in the interior of the weathered crust. Matrix micropores are widely developed, especially the various matrix cracks formed by tectonics and weathering, as well as the stress characteristics of small dissolved pores, and physical properties such as porosity and permeability. This ‘dual structure’ developed in the bedrock is important for guiding the exploration of the lake basin bedrock for natural gas.