The invention discloses a high-airtightness liquid flowmeter. A sensor portion can be effectively sealed at a signal line interface by a wiring seal structure, and the seal structure can avoid failure in sealing under low-temperature environments to realize operational stability of the sensor portion so as to guarantee performances of the whole flowmeter. Mass of enameled wires is not attached onto test tubes, so that test precision of the test tubes cannot be affected. Two ends of each enameled wire are welded firmly and prevented from shedding, and accordingly operational stability of the flowmeter can be improved. The test tubes in two rows are in a similarly triangular form to enable the flowmeter to be integrally compact in structure and attractive in appearance, and by adoption of the double-tube structure, external vibration sensitivity can be lowered, phase difference measurement can be realized easily, and accordingly higher measurement precision can be achieved. Moreover, the high-airtightness liquid flowmeter is simple, compact, simple and feasible in operation, more reliable in airtightness, wide in application range and suitable for popularization and application.