Department of Mathematics,Anhui Normal University,Wuhu 241000,China;
College of Mechanical and Electronic,Kaifeng University,Kaifen9 475000,China;
Department of Mathematics,East China University of Science and Technology,Shanghai 200237,China;
Department of Mathematics,Anhui Normal University,Wuhu 241000,China;
backward stochastic differential euqation; barrier; penalization method;