By using molecular beam epitaxy PtMn/Ni80Fe20 bilayers were prepared on Mo(100) seeding layer on MgO(100) substrate. X-ray diffraction showed that the PtMn/Ni80Fe20 bilayers were mainly grown as (110) bicrystal films with 90° twin domains. The exchange anisotropy was studied by angular dependent magneto-optical Kerr effect. The results indicate that the PtMn/Ni80Fe20(110) bicrystal films possess biaxial exchange anisotropy with exchange field up to 130 Oe.