The present disclosure discloses a medium transmission test device and a method for concrete under a temperature-osmotic pressure-load coupling effect. The device includes a loading device and a water pressurization device; the loading device includes a press, an upper steel plate and a lower steel plate used for clamping a test block, and a fastener that connects the upper and lower steel plates; the upper steel plate includes a first steel plate and a second steel plate; a spring is sleeved on a screw between the first steel plate and the second steel plate; the water pressurization device includes a liquid storage tank, a pressurization pump, a liquid storage pool, a connecting pipe for communicating the pressurization pump to the liquid storage tank, and a connecting pipe for connecting the pressurization pump to the liquid storage pool; the liquid storage tank is provided with an open end; and a tank port of the open end is fixedly connected to a side surface of the test block. The present disclosure achieves a load-temperature-osmotic pressure coupling effect on concrete, can well simulate a complicated severe environment where underground concrete is located, and provides an effective device support for the study of the durability of concrete under complicated severe conditions.