The utility model relates to a quadrature opposite sex decking U -shaped rib and panel splice fatigue test device, including test piece, test piece restraint device, loading device, controlling means, data acquisition device and computer, the test piece is fixed on the test piece restraint device, loading device includes actuator and load sharing roof beam, controlling means connects perpendicular effort is applyed to the actuator, applys on the panel of test piece through load sharing roof beam symmetry, the data acquisition device is with data transfer to computer, the computer link and the controlling devic. Through the device carries out fatigue test, the reaction U -shaped rib that can be comparatively accurate and the actual stress state of panel junction, and the deformation of its panel and U -shaped rib also is close with the actual state.