The invention provides a P2P (peer-to-peer) network based construction personnel safety monitoring method and system. The method includes: deploying a P2P network, which comprises a monitoring node and a plurality of monitored nodes, on a construction site on basis of mobile terminals carried by construction personnel; allowing the monitoring node to transmit, in sequence, a poll request to the monitored nodes in a monitoring object information table; after receiving the poll request, allowing the monitored nodes to feed position information back to the monitoring node; allowing the monitoring node to judge whether or not the monitored nodes are in the safety construction area according to the position information fed back by the monitored nodes. The monitoring node and the monitored nodes are divided according to roles of the construction personnel. The method and the system according to the embodiment have the advantage that site safety is provided with certain guarantee.