A new simple method to decouple a 1×2 MIMO dielectric resonator antenna (DRA) by loading a dielectric sheet (DS) on the upper surface of the dielectric resonator (DR) at the lateral side is proposed. The 1×2 MIMO DRA adopted a double-layer dielectric substrates structure to optimize impedance matching and radiation characteristics. The edge-to-edge distance between the two DRs was 0, and the antenna operated in the millimeter wave frequency band. The loaded DS caused the E-field within the DR to redistribute and concentrate towards the DS loading area and within the DS, thereby weakening the field strength coupled to another DR unit to achieve decoupling effect. The simulation results based on ANSYS HFSS software show that the -10dB impedance matching bandwidth of the antenna is 25.6% (22.75~29.43GHz), and a maximum isolation enhancement about 30dB is achieved within the impedance matching bandwidth.