A horizontal automatic submersible pump includes a capacitive liquid level sensor, a circuit board and a motor. The capacitive liquid level sensor is arranged inside a casing of the horizontal automatic submersible pump. The capacitive liquid level sensor is configured to detect a liquid level outside the casing of the horizontal automatic submersible pump. The output terminal of the capacitive liquid level sensor is connected to the input terminal of the circuit board. The control terminal of the motor is connected to the output terminal of the circuit board. The circuit board is configured to control the motor to work or stop according to a detection signal of the capacitive liquid level sensor. The horizontal automatic submersible pump starts and stops automatically, and the capacitive liquid level sensor means there are fewer moving parts, which makes the pump less expensive to manufacture, more dependable and longer lasting.