Based on the accurate singlet and triplet state interatomic potentials for Na2, a theoretical study of elastic scattering properties of sodium atoms at ultracold temperatures is reported in this paper. The s-wave scattering length, effective range, the p-wave scattering length and the number of bound states are calculated. The singlet and triplet elastic scattering cross section between sodium aotms at ultracold temperatures are dominated by s-wave scattering, and shape resonances occur with collision energy increasing. There exist pronounced f-wave and i-wave shape resonances for the singlet and triplet cross section. In addition, s-wave scattering length is calculated by using the degenerate internet state approximation for selected hyperfine states of sodium atoms. The results are in agreement with calculated values obtained by close-coupling method.