Abstract: Based on the concept of correlation coefficient, this paper introduces an evaluation method of barrage jamming effect on ISAR. This method can reflect clearly distortion degree of the jammed target during the whole jamming process. Also, it make the evaluation of jamming effect quantify from zero to one. it has the merit of unitary. Furthermore, Two typical noise barrage jamming modes are employed in computer simulation of interference with ISAR. The result shows the method proposed is effective.