The invention relates to a deep sea multi-column mooring floating platform vortex-induced motion pool test device. The device comprises a trailer, a longitudinal motion guide rail mechanism, a transverse motion guide rail mechanism, a yawing rotation mechanism, an optical measurement mechanism and a top plate for mounting a floating platform model; a longitudinal elastic piece for determining thelongitudinal rigidity is further arranged between the trailer and the transverse motion guide rail mechanism; a transverse elastic piece for determining the transverse rigidity is further arranged between the transverse motion guide rail mechanism and the yawing rotation mechanism, and an elastic restraining piece for determining the rotating rigidity is further arranged between a yawing rotatingsupport and a connecting main shaft. Compared with the prior art, the test device not only can accurately and equivalently simulate the three-degree-of-freedom rigidity of a mooring system in the horizontal plane under the actual sea condition, but also can simulate the vortex-induced motion response characteristic of a deep sea platform under the nonlinear rigidity equivalent constraint.