The Global Navigation Satellite System (GNSS) has been widely used in many fields, such as positioning, navigation and timing applications. Aiming at the case of four satellites in GNSS positioning, a direct-solution method based on the decoupling leading terms elimination (DLTE) has been developed for positioning calculation in this paper. This method reduces the single-point positioning problem to a simple mathematical problem of finding solutions to a set of equations. In comparison with the traditional Least-squares (LS) method, the method proposed in this paper does not require initial position or iterations. Experiments verify the effectivenss of the proposed method.