Within the framework of strong electron-lattice interaction of Mn3+ ions and orbital dependent exchange interaction model, the crystal and magnetic structures of charge ordered phase La1/3Ca2/3MnO3 are studied. The calculation results are in agreement with the "Wigner crystal" model. The estimated superexchange parameters confirm the qualitative conclusions of experimental works about frustrated magnetic structure with magnetic supercell (3a x b x 2c). The values of hyperfine magnetic fields on 55 Mn nuclei in different charge states in charge ordering phase are calculated.