The invention discloses a wireless sensor network node positioning method based on grid cumulative probability. A target node, anchor nodes S, and a computer are provided. By adopting the prior position information of the target node, the to-be-evaluated position of the target node is limited in a small range, and then in the small range, cumulative probabilities of various grids in the range are calculated according to the path loss of the anchor nodes in different directions and a distance between transceiving nodes, and therefore the accurate position information of the target node is determined. Better positioning precision is provided, and good positioning stability is provided.