Abstract: Current study of backflow of proppant is dominated by physical model experiment. Based on laboratory experiments of the three major parameters including fracture width, closure stress and velocity of flow, qualitative and a few quantitative analyses are carried out. This paper systematically analyzes the four major parameters that influence backflow of proppant, introduces the principles and methods of three sets of oversea experiment apparatuses used to study backflow of proppant. It also presents some proposals.