A combination housing of a notebook computer having a display housing and a main frame housing. The main frame housing including a top metal cover, a first middle plastic frame, and a bottom metal cover three of which are combined to form a sandwich structure. Meanwhile, the main frame housing including a front metal cover, a second middle plastic frame, and a rear metal cover three of which are combined to form a sandwich structure. Besides, an engagement of engaging parts of the metal covers in corresponding arched cavities of the middle plastic frames is utilized to permit a rapid fastening. In this way, the main housing portion of the notebook computer can be made of aluminum ally or aluminum magnesium alloy.