Medium effects on the flow of strange particles in heavy ion collisions

Strange particles such as the kaon and lambda are useful in probing the properties of dense matter formed in heavy ion collisions. We review in this talk the theoretical understandings of their properties in nuclear medium based on both the effective chiral Lagrangian and the phenomenological hadronic model. We further review the effects due to changes in their in-medium properties on their collective flow in heavy ion collisions.