This paper proposes a decoupled-control method of normal and thrust forces in single-sided linear induction motor (SLIM) which is based on a unified concept of machine principle. This method is derived from the analytical formulas for normal and thrust forces of a SLIM. This method can be applied to a LIM vehicle system, in which the normal force is used to levitate and the thrust force to propel a LIM vehicle without force-couple of LIM. By using this method, a compact combined levitation-and-propulsion system with LIM only can be realized. This method is verified by a successful simulation of levitation and propulsion for a SLIM model vehicle ME01 running under water in our Laboratory.