The invention, which relates to the technical field of construction safety, discloses a method, a controller and a system for safety protection at a construction site. The method comprises the following steps that: a current position of a wristband is obtained in real time, wherein the wristband is worn by a construction worker; whether the obtained current position of the wristband is located ina preset dangerous area is determined; if so, whether equipment in the dangerous area is in an activated state is detected; when any equipment in the dangerous area is detected to be in an activated state, an early warning signal is sent to the wristband, so that the wristband carries out alarming. With the disclosed method, when the construction worker approaches the equipment in an activated state at the construction site, the construction worker is warned timely, so that a phenomenon that the construction worker is injured by mistake when approaching the equipment in a running state by mistake is avoided effectively and thus the safety of the construction worker is guaranteed and the potential safety hazard of construction at the construction site is reduced.