The invention discloses a wireless sensor network early warning method and system based on clustering compressed sensing. The method comprises the following steps: S1) calculating optimal cluster number and optimum cluster head space distribution by a gateway according to geographic position and an energy consumption model of each sensor node in a wireless sensor network; S2) obtaining monitoring data in a cluster, and converting the monitoring data into binary reading and a binary bit string sequence according to a threshold value; S3) carrying out dense random projection and sparse random projection thereon to obtain a compressed sensing sequence, and carrying out reconstruction on the compressed sensing sequence to obtain a reconstructed sequence; S4) carrying out judgment according to estimated value of the reconstructed sequence, and summarizing the number of effective neighbor nodes executing a majority vote method; and S5) if the number of the effective neighbor nodes is larger than a preset threshold value, determining that the node has an abnormal event. Real-time performance and fault tolerance of the monitoring method can be improved; influence of the fault nodes on abnormal event detection reliability is reduced; and network energy consumption in the data collection process can be reduced.