In order to solve the problem of low SNR(signal to noise ratio) radar imaging under short observation time, a compressive sensing inverse synthetic aperture radar imaging technique based on echo covariance matrix processing was proposed. The method constructs the compressive sensing problem model under the echo covariance matrix, and reduces the influence of noise on the imaging results through a specific linear transformation. By processing the simulated echo data under the condition of short observation time and low SNR, the method obtained target imaging results with higher quality and higher contrast than the traditional compressive sensing method. In the simulation experiment, the target background ratio and the background noise energy of the imaging results are better than the traditional methods, which verifies the validity of the method.