A differentially-fed circular patch antenna under dual high-order modes for enhanced bandwidth and stable high gain is proposed in this paper. The current distribution of TM31 mode is reconstructed by loading two open slots at the edge of patch, by which the broadside radiation of TM31 mode is substantially increased. By loading an additional slot in patch's center, the current of TM12 mode is reshaped to be more in-phase, and so the sidelobe radiation is dramatically reduced. The resonant frequencies of TM31 and TM12 modes are then reallocated and get close to each other due to the loading of slots and shorting pins, which finally contributes to an enhanced bandwidth of 12.9%. Moreover, the antenna produces high gain up to 13.7 dBi, while the beamwidth and gain level are kept stable in band.