The invention discloses a four-point bending load tester suitable for a biological sample of micro CT, and aims to provide a four-point bending loading device which aims at the biological sample and meets the use requirements of the micro CT. The four-point bending loading device comprises a loading cavity outer cylinder, a bottom cover, a micrometer head, a shaft coupling, a sensor base, a sensor, a spacing block, a movable pressure head and a fixed pressure head. The outer cylinder is connected with the bottom cover to form a loading cavity, and the micrometer head passes through the bottom cover and is connected with the sensor base through the shaft coupling. One end of the sensor is fixed on the base, while the other end is connected with the spacing block. The spacing block applies load to the movable pressure head through an arc-shaped bulge. The spacing block, the movable pressure head and the fixed pressure head are coupled with one another to determine loading positions. The four-point bending loading device overcomes the defects of oversize and artifacts of materials in the prior art, and successfully provides a controllable four-point bending load for the biological sample inside the micro CT without generating the artifacts, so that correlative research works can be carried out.