Abstract: Research purposes: The compression characteristics of unsaturated cohesive soil is an important calculations parameter used in subgrade engineering, foundation engineering, underground engineering and slope engineering design calculations. In order to define the influence of matric suction on the one - dimensional compression characteristic， a series of one - dimensional compression tests are carried out under controlled matric suction and increasing the net vertical stress for the unsaturated cohesive foundation soil in Hefei area. Research conclusions ： (1) The e - lgg curves in different matric suction were composed of two straight line segments， and the net vertical stress of 300 kPa was the cut - off point. (2 ) The relationship between compression index and the matric suction fitted the Barcelona model； Compression index and tangent compression coefficient decay exponentially with the increasing matric suction. ( 3 ) The concepts of suction tangent compression coefficient are proposed. The suction tangent compression coefficient showed exponential relationship with the net vertical stress. (4 ) The research result can provide theoretical reference to the engineering characteristics of the unsaturated cohesive soil bed.