The invention provides a vacuum degree low pressure alarm. A power switch is connected to a live wire of a 220V power line. A power indicating lamp is connected to a null line. A buzzer and an alarming lamp are connected to a guide line between the null line and a relay contact. An electric contact pressure gauge is connected to a guide line between the null line and a relay coil. A normal-workingindicating lamp is connected to a circuit between the null line and the relay contact. When the power switch K is turned on, the power indicating lamp is lit up, and a relay is closed; when the vacuum degree is lower than a set value, the buzzer and the alarming lamp are electrified; when the vacuum degree is higher than the set value, the buzzer and the alarming lamp are powered off, and the normal-working indicating lamp is turned on. The electric contact pressure gauge is connected to an electronic circuit of the alarm, the relay is closed when the vacuum degree is lower than the set value, a common terminal circuit is turned on, the buzzer buzzes to make prompt, and the alarming lamp is lit up to give warning. Through sound and light warning, vacuum degree problems can be handled timely, and product quality can be guaranteed, so that the sound and light warning is suitable for being applied to the vacuum degree low pressure alarm.