Abstract: By using Jones matrix method, it is derived that polarization converter with two variable retarders oriented at 0 and -45 transforms random polarization state to horizontally linear polarization, and the expression of retardation is given. Liquidcrystal variable retarder (LCVR) was developed, and the retardation was linearly proportional to applied voltage ranging from 1V to 2.7V. In addition, polarization converter based on two LCVRs was designed, and it was able to change any given polarization state (Stokes parameters described as (-0.567，0.752，0.36)) to horizontally linear polarization state (Stokes parameters described as (1，0，0)). The theoretical analysis and experimental result are presented.