The invention provides a data transmission method and device based on compressed sensing under a slow time-varying channel. The method comprises the steps of receiving compressed data transmitted by the slow time-varying channel; obtaining an initial channel estimation matrix via a channel estimation algorithm according to pilot frequency data inserted into the compressed data; carrying out reconstruction on original data of the compressed data by employing a disturbance reconstruction algorithm according to the channel estimation matrix and a disturbance matrix to obtain reconstructed original data; and obtaining updated channel estimation matrix according to the reconstructed original data and the compressed data, wherein the updated channel estimation matrix is used for carrying out the reconstruction on the received compressed data. According to the data transmission method and device provided by the invention, the demands on a pilot frequency are effectively reduced; and the transmission efficiency of a system is improved, namely the system performance is improved.