The invention discloses a recyclable air pressure type wellbore annulus liquid level detection device. According to the recyclable air pressure type wellbore annulus liquid level detection device, through cooperation between one part fixed to the ground surface at the inlet and the other part floating in the annulus between the well wall and the drill rod in a wellbore under the action of buoyancy, the distance between the annulus liquid level and the well mouth is measured repeatedly, and the rising distance of the annulus liquid level is calculated. Thus, detection of the liquid level inside the wellbore annulus is realized, equipment and technical support is provided for well leakage or kick detection under well repair operation and shut-in conditions, guarantee is provided for operation under well repair and shut-in conditions safely and efficiently, and the timeliness and accuracy of drilling complex condition monitoring are improved.