The invention discloses a proportional overflow and throttle valve. Switching between an overflow mode and a throttle mode is realized through a structure adopting cooperation between a pressure difference feedback valve sleeve and a main valve core. When the oil pressure at a main oil inlet is higher than that at a main oil outlet, a valve body works in the overflow mode; when the oil pressure at the main oil inlet is lower than that at the main oil outlet, the valve body works in the throttle mode. Automatic switching between the overflow mode and the throttle mode is realized through operating pressure difference change of the pressure difference feedback valve sleeve. The proportional overflow and throttle valve overcomes defects in the prior art, and the valve body can switch between an overflow valve structure and a throttle valve structure by regulating pressure difference, so that the valve body is used more flexibly and practically.