The low-coherence light interferometry is used to avoid the spurious fringes when the surface profile of optical parallel plates is tested by laser interferometer. The sodium light, a low coherence light, is used on the Twyman-Green interferometer, therefore the lights reflected from the front and rear surfaces of optical parallel plates will not interfere with the reference light simultaneously. So the spurious fringes are avoided. The captured interferogram is processed with the virtual grating phase-shifting moiré fringe method. The front suface of a parallel plane is measured using Zygo phase-shifting interferometer, whose result coincides with the one obtained by the Twyman-Green interferometer.