The invention provides a chloride-free enhanced slump-retaining cement grinding aid which comprises, by weight, 2-8 parts of diethanolisopropanolamine, 6-20 parts of triethanolamine, 10-25 parts of sodium formate, 0.5-2 parts of organic phosphonate retarders, 0.5-2 parts of polymeric dispersing agents, 2-4 parts of green syrup and the rest water. The grinding aid has the advantages that the diethanolisopropanolamine, the triethanolamine and the sodium formate are used in a matched manner, the early strength and the later strength of cement are remarkably improved, the organic phosphonate retarders and the polymeric dispersing agents are used in a matched manner, so that the cement has excellent slump-retaining performance, adaptability between the cement and a concrete additive is good, the early strength and the later strength of the cement are improved by 3-5MPa in actual use process, adaptability among the cement, a naphthalene water reducer, an aliphatic water reducer and a polycarboxylic acid water reducer is good, the cement paste fluidity cannot be lost within 2 hours, and the grinding aid does not contain any chloride ions and sulfate ions, is free from toxicity and corrosiveness, green and environmentally friendly and cannot damage to human bodies, buildings and the like.