In order to reduce the sensitivity of the polarization beat length with wavelength and expand the operating bandwidth of the polarization device made by the holey fiber, the holey fiber with diamond lattice, the influence of the special holes near the core, the bottom holes and the pitch of diagonal holes on the wavelength sensitivity of polarization beat length are analyzed. The preliminary optimal cladding structure parameters are obtained. The polarization beat length remains stable in a wide wavelength range. The results show that the relative variation of polarization beat length is less than ± 4% in wavelength range of 1.2~1.7 mm and the operating bandwidth can reach 500 nm while the error tolerance of optimized geometric parameters is greater than 0.1 mm. The more feasible process structure parameters are provided for drawing the achromatic holey fiber wave plates with broadband.