A metamaterial-enhanced dual-polarized antenna based on two half-mode SIW (HMSIW) resonators is presented. The dual polarization operation is realized by two orthogonally arranged HMSIW elements fed by the coaxial line probes. The isolation and the peak gain of the MIMO antenna are improved by a 2x8 metamaterial (MTM) array between the two HMSIW elements. The simulated isolation of this antenna is higher than 23 dB within the operation bandwidth and the maximum gain achieves 6.8 dBi for each polarization. This dual polarized HMSIW antenna has compact size and low profile and is suitable for Multiple-Input-Multiple-Output (MIMO) communication terminals.