A data transmission cross-layer optimization algorithm based on compressive sensing isproposed to solve the problems of data transmission in WSNs. Firstly, a spatiotemporal dynamic sensing matrix is constructed to exclude spatiotemporal redundancy of data, which reduces sampling frequency and makes sampled data contain all useful information. Then, according to the objective of the minimum transmission data, a cross-layer optimization model is established based on the constraint conditions of link capacity, power and routing selection. The optimal power control, link capacity and routing selection schemes are obtained by solving the optimization model. Simulation results show that the algorithm reduces the amount of data transmission, and overcomes the congestion caused by unbalanced data processing problems in the traditional algorithm.