Non-contact measurement system and method for liquor level in closed container

The invention relates to a non-contact measurement system and method for the liquor level in a closed container. The system comprises an optical fiber femtosecond laser, a pump light path, a detection light path, a terahertz detector, an acquisition card and a computer; the optical fiber femtosecond laser inputs laser to the pump light path and the detection light path through two optical fibers respectively; a reflector in the pump light path is parallel to the closed container to be detected, terahertz waves outputted by a terahertz source in the pump light path are vertically incident into the closed container to be detected through the reflector, and terahertz time-domain signals containing liquid level information are inputted into the terahertz detector, the terahertz detector inputs the terahertz time-domain signal containing the liquid level information into the acquisition card, the acquisition card inputs the terahertz time-domain signal containing the liquid level information into the computer, and