This paper presents a comparative study of two different expressions for magnetization curve in simulating dynamic performance of an autonomous three-phase self-excited induction generator (SEIG) supplying a single phase load. An excitation capacitor and a single-phase load are properly connected across the phase winding of the studied Y-connected SEIG. An approach based on a three-phase induction machine model is employed to derive dynamic equations of the studied SEIG. The magnetization curve of the excitation current Iφ versus magnetization reactance Xm, is respectively expressed by a linearlized equation based on piecewise linear approximation and a polynomial based on curve fitting method. Experimental results obtained from a laboratory 1.1 kW induction machine driven by a DC motor are also performed to confirm the feasibility and effectiveness of the analyzed results. It can be concluded from the experimental and simulated results that the dynamic simulations using the proposed polynomial based on curve fitting method are much closer to the experimental results than the ones using the piecewise linear approximation.