Airtightness detection mechanism

The utility model provides an air tightness detection mechanism. The air tightness detection mechanism is characterized in that an air tightness substrate is provided with a groove along the width of the air tightness substrate; the telescopic mechanism is arranged below the airtight substrate, the upper end of a telescopic rod of the telescopic mechanism is provided with a plug, and the plug is matched with a hole part of an upper cover to be detected; the gas circuit assembly is arranged below the airtight substrate; and the air pressure detection piece is arranged below the airtight substrate. According to the airtight substrate provided by the utility model, short upper covers and long upper covers can be detected; when a short upper cover needs to be detected, the short upper cover is directly arranged on the airtight substrate; in addition, the turnup of the airtight substrate is clamped and embedded in the groove, so that the upper cover and the airtight substrate are ensured to be attached. 本实用新型提供一种气