Automatic water injection device based on oil field well

The utility model discloses an automatic water injection device based on an oil field well, which comprises a water inlet pipe, a horizontal slide way arranged on the side wall of the water inlet pipe, a slider in the horizontal slide way in a sealed sliding manner, a control button arranged on the outer side of the water inlet pipe, a spring fixedly connected to the surface of the control button, and the spring connected with the slider. The section, stretching into the water inlet pipe, of the lower sliding block in a natural state is a stretching-in section, the bottom side of the stretching-in section is an inclined face, and a vertical sliding body is arranged below the stretching-in section and connected with a floating body. Automatic water injection is achieved according to changes of the water level, water injection is stopped after the specified height is reached, water injection is conducted again when the water level drops obviously, the water level of an oil field well is more stable, and the use