The lattice parameters, total energy, magnetism, density of states, and band structure in the multiferroic material DyMnO3 with orthorhombic structure are investigated by using different magnetic models, and the non-collinear magnetism and the collinear magnetism are taken into account by using density functional theory combined with the projector augmented wave method via the software package of VASP. The generalized-gradient approximation (GGA) pseudo potential is used in the calculation, and the local spin density approximation +U method is also adopted to deal with the strong correlation effect of the 3d electrons. The results show that Mn ion in the AAFM magnetic model has the lowest energy and is the most stable, while the weak magnetism of the rare earth ion Dy can be neglected, and that the total energy and the magnetic moment of DyMnO3 in orthorhombic structure increase when the non-collinear magnetic structure of Mn ion is considered and that the DyMnO3 material is an indirect-gap insulator with an energy gap value of 0. 38 eV obtained from GGA or 1.36 eV from GGA+U, and the lattice distortion should be considered to be due to the hybridization between Mn-3d and O-2p electrons, which can be analyzed from the density of state.