Abstract: A test method of unsaturated seepage flow of single fracture is presented and an experimental equipment for testing the relationship of capilary pressure,saturat ion and unsaturated permeability of fracture is developed. In order to examine the reliability of experimental provision and the validity of experimental principle,and to expound the mechanisms of unsaturated seepage flow in fracture,a simplified fracture model with flight aperture is developed and an experiment of unsaturated seepage flow in this fracture model is done Mechanisms of unsaturated seepage flow in fracture are expounded initially.At the same time,the experimental results show that the experimental provision and the experimental principle in this paper are reasonable and reliable.