A new approach to thermodynamics has been developed from the following new viewpoints: (1) to recognize that thermodynamics can be composed of three kinds; ＇＇thermodynamics of substance＇＇, ＇＇thermodynamics of process＇＇ and ＇＇thermodynamics of system＇＇; (2) to introduce a heat source, a heat sink, a work source and a work sink, making the description of the first and second laws of thermodynamics quite clear and compact; (3) to propose a graphical method of using ＇＇thermodynamic compass＇＇. This clearly indicates not only Delta H and Delta S (or Delta epsilon), but also its ratio (A = Delta epsilon/Delta H), are quite important; (4) to introduce ＇＇water model＇＇. It can give an interpretation of the first and second laws of thermodynamics, suggesting that the energy level A is an important concept.