The utility model discloses a heavily stressed test device that stews of constant velocity cardan joint assembly for car, including clamp used for test, clamp used for test's hole have with the outerinvolute spline assorted of the stiff end stalk portion of constant velocity cardan joint assembly in involute spline, its characterized in that: it still includes stress sheet formula accelerometer and data acquisition and recording display instrument, stress sheet formula accelerometer fixes on clamp used for test's outer wall, and its information output end connects the signal input part of data acquisition and recording display instrument. Use the utility model discloses test the accurate actual failure time that know constant velocity cardan joint assembly for the car of ability to accomplish the design of constant velocity cardan joint assembly as early as possible.