The term has generally been reserved for declining renal function in the setting of advanced congestive heart failure.Considering the complex and bi-directional relationship between the heart and the kidneys,Professor Claudio Ronco divided the cardiorenal syndrome into five subtypes:type I,acute cardiorenal syndrome;typeⅡ,chronic cardiorenal syndrome;type Ⅲ,acute renocardiac syndrome;type Ⅳ,chronic renocardiac syndrome;and type V,secondary cardiorenal syndrome.Cardiorenal syndrome is very difficult to copy with in chronic renal failure and chronic heart failure.This article reviews progress of cardiorenal syndrome in its clinical research.