The "hard" pulse sequences with spin echo for one dimensional homonuclear correlation editing (1 D HCE) are discussed with density operator theory. The experimental results coincides with the theoretical expectation. It is shown that the correlation obtained from I D HCE spectra is similar to that from COSY. The advantages of this technique are: 1) saving time, 2) saving computor memory, 3) keeping the sensitivity, resolution and the fine structure of 1 D NMR spectra.