The invention discloses a manual clamping mechanism comprising a machine base, a handle, a pressing arm, an upper chuck and a lower chuck, wherein the upper chuck is arranged at the suspending end of the pressing arm of the machine base; the lower chuck is arranged on the machine base; the upper chuck comprises a pressing rod and a pressing head; the pressing rod and the pressing head are connected through an elastic mechanism; the pressing rod is fixedly connected with the suspending end of the pressing arm; a moveable pressing block is arranged at the lower end of the pressing head; the moveable pressing block and the pressing head are connected through a hinged structure; and a limiting structure for limiting the swinging angle of the moveable pressing block is arranged on the pressing head. The structure of the manual clamping mechanism can adapt to the appearance change of parts; the problems of deformation or local indention and the like which occur in the welding process easily and can influence the product quality are solved well; and high practical value is achieved.