The core production horizon of mid-deep geothermal wells in Tianjin is the Wumishan Formation of the Jixian System. Dominated by calcareous dolomite and dolomite, this formation features highly developed fractures due to long-term regional tectonic activities, which easily leads to drilling fluid lost circulation during drilling operations. Such accidents cause construction delays, cost increases, and potential geothermal reservoir contamination, impairing well completion quality and reinjection efficiency; they are urgent hot and difficult issues to be addressed in this field. Based on the supervision practice of Well BD-07B in Block Bao 10, Baodi District, Tianjin, this paper analyzes the causes, types and hazards of lost circulation by integrating geological survey, well completion and supervision data. A whole-process prevention-control system of “advanced prediction – graded prevention – accurate treatment” is established with supervision experience, and key supervision control points are defined. The results show that lost circulation in Well BD-07B is caused by the combination of developed rock fractures, mismatched drilling fluid properties and non-standard construction operations. By using optimized plugging drilling fluid, precisely adjusted drilling parameters, targeted lost circulation control technologies, and full-process supervision, the treatment period of lost circulation can be shortened by more than 40%, the cost reduced by 25%, and geothermal reservoir pollution decreased. This research targets the pain points of lost circulation, providing practical references for the prevention and control of lost circulation and standardized supervision of similar geothermal wells in Tianjin and surrounding areas. It has important engineering application value for promoting the efficient, green and sustainable development of geothermal resources.