A liquid composite spring and a method for adjusting stiffness and damping property of the liquid composite spring such that the liquid composite spring includes an outer sleeve; a core shaft arranged around an upper portion of the outer sleeve. An upper portion of the core shaft is located inside the outer sleeve, while a lower portion extends out of the outer sleeve; an upper liquid chamber formed in an upper space inside the outer sleeve and having a lower portion connected to a top end of the core shaft; and a lower liquid chamber formed in a lower space inside the outer sleeve and connected with the core shaft. The core shaft has a damping flow channel arranged therein, for communicating liquid in the upper liquid chamber with liquid in the lower liquid chamber. The liquid composite spring can provide vibration-reducing effect and change stiffness and damping effect.