The invention relates to a high-limestone-flour-adulterate-amount composite enhanced grinding aid for cement and a preparation method of the high-limestone-flour-adulterate-amount composite enhanced grinding aid. The preparation method comprises the following steps that 1, materials including 18%-25% of triethanolamine, 8%-15% of triisopropanolamine, 20%-28% of ethanediol, 8%-12% of molasses, 4%-8% of polycarboxylate superplasticizer, 6%-10% of sodium sulfate, 5%-8% of glacial acetic acid and 2%-24% of water are taken; 2, the water is poured into an agitator kettle, and sodium sulfate is added to be stirred till sodium sulfate is completely dissolved; 3, glacial acetic acid is added to be completely dissolved, triethanolamine, triisopropanolamine, ethanediol, molasses and polycarboxylate superplasticizer are sequentially added after glacial acetic acid is dissolved, stirring continues to be carried out for 20-30 minutes, and the high-limestone flour-adulterate amount composite enhanced grinding aid is obtained. The high-limestone-flour-adulterate-amount composite enhanced grinding aid has the advantages that cement particles are prevented from clustering, and the cement particles are kept in a high homodisperse state; the strength of an interfacial transition zone is increased, and the strength of the cement is further increased; the grinding aiding efficiency of the grinding aid is improved.