Spacetime adaptive processing (STAP) is widely used in airborne early warning radar. For this, the study of its interference is of great significance. A jamming method based on clutter is proposed. Being easy to be detected by using a mainlobe to mainlobe way to intercept radar signals by conventional coherent jamming methods, a jammer is located in the sidelobe of the radar to intercept the clutter signal rather than the direct signal as the source of the coherent jamming signal. The jamming is carried out by scattering to realize the main lobe jamming. The calculation formulas of radar direct wave power and radar clutter power received by the jammer are derived. A clutter signal model and a jamming signal model are established. Through simulation, the power of radar direct wave and radar clutter received by the jammer are compared, and the feasibility of clutter signal interception is verified, and compared with pseudo clutter jamming through simulation. The simulation results show that compared with the pseudo clutter jamming, the proposed method has a lower requirement for the accuracy of the prior information of the target, is feasible, and effective to the false targets formed in both azimuth and Doppler frequency after jamming.