This paper proposes a method for evaluating salt-logging and desalination status and salted-soil improvement in irrigated areas with harmful salt content (HSC) and its drainage-diversion ratio (DDR) instead of previous solids (TDS) and its DDR as the index. This method is of pertinency and authenticity. Through water-salt balances calculation, it is verified that the DDR of HSC is 1.7 times that of TDS. It is also revealed that the irrigation area has been in the desalination status in the past 35 years. The drainage-diversion difference of HSC is positive and, as a result, 13.76 million tons of accumulated HSC have been discharged from the irrigation area. The drainage-diversion difference of non-HSC is negative, and hence 6.4 million tons of accumulated non-HSC have deposited in the irrigated area. This is of theoretical significance and practical value in regulating DDR of irrigation and cutting down the Yellow River diversion. Increasing groundwater portion of ditch drainage water is an important way to speed up desalination and salted soil improvement in irrigation areas.%本文提出用有害盐量及其排引比取代以往惯用的盐量及其排引比，作为评价灌区积、脱盐和盐渍土改良的指标。从而计算并证实了有害盐量排引比约为盐量排引比的1.7倍。指出35 a来灌区土壤经历着脱盐淡化的进程，有害盐量排引差为正值，累计排出灌区的有害盐量为1 376×104 t；而无害盐量排引差为负值，累计堆积于灌区的无害盐量为640.8×104 t，这对调整灌区水量排引比和减少引黄水量具有重要实用价值。而提高沟排水中地下水排泄量的比例是加快灌区脱盐和盐渍土改良的重要途径。
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