A novel two-step phase-shifting profilometry is proposed after the Gram–Schmidt (GS) orthonormalization is introduced into three-dimensional (3D) shape measurement. Firstly, two phase-shifted randomly sinusoidal fringe patterns are projected onto the tested object by Digital-light-processing (DLP) projector. The fringe patterns modulated with theobject’s surface are captured by a CCD camera. Secondly, the background component is eliminated from deformed gratings by averaging method pixel by pixel after the appropriate window size is adopted. Thirdly, an orthonormalized fringe basis is determined from the two fringe patterns using the GS method. Then, the phase is demodulated from the fringe basis. Finally, we have tested the proposed method with real measurement of the human mask. Our algorithm is compared with the other methods. The experimental results are given, which demonstrate the validity of our method.