The invention discloses a photoelastic test three-directional uniformly-distributed force loading device. The photoelastic test three-directional uniformly-distributed force loading device comprises a base and a counter-force frame arranged on the base, wherein the counter-force frame is connected with a bottom sprag; a space formed by the bottom sprag and a load-dividing loading plate device together is used for placing a photoelastic model; the three-directional load-dividing loading plate device is limited through a positioning plate; the load-dividing loading plate device is connected with one end of a universal retention loading mechanism, and the other end of the universal retention loading mechanism is connected with the counter-force frame through a worm-screw jack device. According to the photoelastic test three-directional uniformly-distributed force loading device, three-directional load-dividing uniformly-distributed force load is realized for the photoelastic model with a relatively large plane; the photoelastic model with load fluctuation has the effects of loading force direction self-regulation and loading force retention, and a sensor is supported to output the numerical value of load; and the device is simple in structure and convenient to operate.