The invention discloses an automatic irrigator which is composed of a nozzle, a control switch, a main switch, a water receiver, a valve switch, a power line, a water pipe and a humidity sensor, and is characterized in that the nozzle is arranged on the surface of the upper end of the irrigator and is used for sprinkling water; the control switch and the main switch are symmetrical to each other, are positioned on the side surface and are used for controlling the sprinkled water amount and controlling on-off of the irrigator; the water receiver is positioned in the middle of the irrigator and is used for storing the water for irrigation and displaying the current residual water amount of the irrigator at the same time; the valve switch is used for controlling whether sprinkling irrigation is needed; the power line is used for providing power for the device; the water pipe and the valve switch are connected together; when the valve switch is turned on, tap water can be injected into the water receiver through the water pipe, and the humidity sensor is positioned at the bottom of the irrigator and is used for reading a humidity value of soil.