A handheld constant-stiffness ring shear apparatus comprises a base (1) and an annular steel frame (2) sleeved inside the base (1). An upper cover (3) is buckled at the top of the steel frame (2). A pressure transfer plate (6) is fixed at an upper portion of the upper cover (3). A rotating shaft (4) is vertically provided at a center of the base (1). The rotating shaft (4) passes through and is fixed with the pressure transfer plate (6). A wrench (13) is fixed at a top end of the rotating shaft (4), and is embedded with a data display meter (14) thereon. A spring bracket (5) is fixed on a side wall of the base (1). A spring guide rod (8) is vertically fixed below the spring bracket (5). A stop nut (10) is sleeved at an upper end of the spring guide rod (8). A spring (9) is sleeved on the spring guide rod (8) below the stop nut (10). A sliding block (7) is pressed by a lower end of the spring (9), and is arranged on the pressure transfer plate (6). A first clamp (11) is connected between an upper end of the sp
