A two-dimensional dusty plasma lattice in an rf discharge was observed. The structural and dynamical properties were analysed by computing pair correlation function, static structure factor, bond-orientational correlation function and mean square displacement. The bond-orientational correlation function was found to fit into the law of r-0.25,and the mean square displacement experienced "ballistic", "subdiffusive" and "diffusive" regimes, both of which together with the other parameters indicate that the two-dimensional dusty plasma stayed at a state between liquid and solid.