To overcome the phase shift error in phase shifting interferometry, a two-step random phase retrieval approach based on Gram-Schmidt (GS) orthonormalization and Lissajous ellipse fitting (LEF) method (GS&LEF) is proposed. It doesn't need pre-filtering, and can obtain relatively accurate phase distribution with only two phase shifted interferograms and less computational time. It is suitable for different background intensity, modulation amplitude distributions and noises. Last but not least, this method is effective for circular, straight or complex fringes. The simulations and experiments verify the correctness and feasibility of GS&LEF.