The invention relates to the technical field of construction site equipment, and specifically discloses an unauthorized uncapping early warning algorithm. The algorithm comprises the following steps:judging a state of capping or uncapping through data acquired by a pressure switch of a pressure sensing module in a data acquisition module, after receiving a capping event or an uncapping event by adata platform, immediately acquiring a GPS position where the event happens through a GPS positioning module in the data acquisition module, and uploading the data to the data platform in a data processing module through a data transmission module, and by the data platform, performing judgement according to on-duty time and off-duty time set for a project and a project GPS electronic fence. In the algorithm provided by the invention, capping and uncapping of workers are monitored in real time through the pressure sensing module and the GPS positioning module, capping and uncapping are judgedthrough a judging unit set, and in combination with GPS positioning, the position is limited, thus, accuracy of judgement to unauthorized uncapping is improved, people entering into the construction site need to wear a safety helmet and make good preparation of safety protection, thus, unwanted troubles caused by accidents are prevented.