The present invention provides an identifier-based lost people positioning method, system, terminal, and server platform. The method comprises the steps of uploading identification information of a person under supervision to the server platform; and receiving, from the server platform, data information collected by one or more image collection apparatuses in an image collection apparatus group, wherein the data information comprises position information of the one or more image collection apparatuses, and an identifier and an image of the person under supervision that are bound with the identification information. Through adoption of the method, system, terminal and server platform, the lost person under supervision can be positioned accurately without the help of kind-hearted persons in the society, and the method, system, terminal and server platform are easy to implement and are low-cost.