A mini SAS HD connector comprises: front and rear housings combined together, wherein the rear housing comprises first and second rear shell pieces; a positioning mechanism disposed between the first and second rear shell pieces and providing a positioning effect; a first combination mechanism disposed between the front and rear housings and providing a combination effect when the front and rear housings are combined; and combinations of a first inner module, a second inner module and circuit boards. The combination of the first inner module and the circuit board is mounted in the first rear shell piece. The combination of the second inner module and the circuit board is mounted in the second rear shell piece. Stopper mechanisms are provided between the first inner module, the second inner module and the circuit boards, so the circuit boards have no distinct displacement due to plugging and unplugging operations of the connector.