High pressure common rail fuel injection system has already developed into the mainstream of fuel injection systems for diesel engines, and the injection pressure is limited by the capacity of the high pressure pump. The fuel leakage of the piston/cylinder interface is the main factor leading to the pump volumetric efficiency loss and thus to the reduction of the pump performance. A review on the research progress was presented from the prospective of the factors influencing the piston/cylinder interface leakage, and the problems in current research as well as the possible further research direction were put forward.