During the Middle Ordovician, the salt deposits of the Majiagou Formation of the Ordos Basin in North China formed, the halite including various genetic types of fluid inclusion. In this study, fit-testing of primary inclusions was performed to reconstruct the physical and chemical conditions during original halite sedimentation. During the post-sedimentation stage, salt was subjected to elevated temperatures (62-70 degrees C) and pressures of tens of megapascals. From these measurements and mathematical calculations, the gas pressure was identified in the primary fluid inclusions, which allowed us to estimate that the brine column thickness in the salt basin was approximately 40 m.