The present invention relates to rotating-key timber grab, which is connected by asingle hoisting steel cable and attached to the hoisting mechanism of a crane. The said grab is controlled to open and close via the interaction of the rotating key and convex key between the guide and the clutch. When the rotating key meshes with the convex key on the guide, it has 360-deg. angle to the guide axis, and its two perpendicular exerted planes on the head coincide with the contact surface of the convex key. The said rotating-key type clutch is very reliable and safe without breakdown from the failed clutching because of the large bearing capacity and no deformation of its rotating key as exerted mechanism.