The utility model relates to a sucker rod pump pumping well mechanical well mouth automatic dosing mechanism which is characterized in that a solution storage tank (1) and a dosing pump (5) are included, the solution storage tank (1) is connected with the dosing pump (5) through a hose (11), the solution storage tank (1) comprises a tank body, wherein a solution guide pipe (4) connected with the hose (11) is arranged in the tank body, and a solution draining faucet (13) is arranged on the lower portion of the tank body; the dosing pump (5) comprises a barrel, a plunger (6) is arranged in the barrel, a spring (9) is arranged under the plunger (6), a plunger handle (10) is arranged on the plunger (6), the hose (11) is communicated with the barrel through a first check valve (7) which is arranged in the dosing pump (5), solutions can enter the first check valve (7) and can not flow out of the first check valve (7), the lower portion of the barrel is communicated with a second check valve (8), and the solutions only can flow out of the second check valve (8) and can not enter the second check valve (8). The dosing pump achieves solution suction and drainage through up and down movement of the plunger, and the requirements for flexible applications of oilfield sites are met.