The invention discloses an adjustable automatic centering wide plate clamp, comprising a clamp body. The clamp body has a turntable fixed. The turntable has a guide rail arranged in the center in thegroove. The guide rails are symmetrically distributed about the center of the turntable. The guide rail has a first slider and a second slider distributed symmetrically. The first slider and the second slider are fixedly connected to the first clamping plate and the second clamping plate, respectively. The end faces of the first clamping plate and the second clamping plate are each provided with aplurality of threaded holes for fixing the test piece. The adjustable automatic centering wide plate clamp in the invention has low manufacturing cost, compact structure and convenient operation. Thus, the clamp is widely adaptable to a wide plate with a thickness within a certain range, and after positioning and clamping, the wide plate can performing automatic centering clamping. This improvesthe test accuracy and efficiency for tests or tests that use wide plates as the research object and require clamping.