For irregular sensing range of sensor nodes, the paper proposes a randomly deployment wireless sensor network algorithm based on the Delaunay triangulation and grid. In the deployment algorithm, sensor nodes that have already been started are grouped by Delaunay triangulation, which then calculates the target point TP by the TPM algorithm and chooses the TP as a reference point to start a new node. This algorithm adjusts TP in accordance with grid coverage around nodes and the distance between nodes. The paper also proposes a “border reinforcement mechanism” and “obtuse triangle TP-point optimization strategy” to improve coverage effectively. Experimental results show that the proposed deployment algorithm can effectively use randomly deployed sensor nodes. It can quickly raise coverage to 90% or more and has the feature that makes the redundant cover region less, the coverage rate growing fast, and small amount of nodes can achieve high coverage.