The invention discloses a wheelchair seat position and posture adjusting mechanism. The wheelchair seat position and posture adjusting mechanism is characterized by mainly comprising a cross four-rod mechanism a seat lifting mechanism, a seat manually-leveling mechanism, a seat electrically-leveling mechanism, a seat locking mechanism and a control system. The cross four-rod mechanism mainly comprises a right cross rod, a left cross rod, a left sliding block, a right sliding block, a left screw shaft and a right screw shaft. The seat lifting mechanism mainly comprises a seat manually-adjusting lifting mechanism and an electrically-adjusting lifting mechanism. The seat manually-leveling mechanism mainly comprises a leveling handle, a left upper wheel gear, a right upper wheel gear, a left middle wheel gear, a middle shaft, an upper tie bar, a right middle wheel gear, an upper sector gear, a small shaft, a left lower wheel gear and a right lower wheel gear and a long shaft. The electrically-leveling mechanism mainly comprises a leveling motor, a left spur wheel gear, a right spur wheel gear, a short shaft, a lower sector gear, a lower tie bar, a left spur wheel gear, a lower shaft and a right lower spur wheel gear. The seat locking mechanism mainly comprises a cam, a spring ball, a lower sliding block, a left upper spur wheel gear and a right upper spur wheel gear.