The invention discloses a composite concrete grinding-assistant reinforcing agent which is prepared by using the following methods: adding 500kg of polycarboxylic acid copolymer, 90kg of triisopropanolamine, 100kg of triethanolamine, 40kg of propanediol and 70kg of glycol into a reaction container; heating to 50-60 DEG C; stirring for 0.5-1.5 hours to uniformly mix to prepare a mixture No.1; adding 50kg of esterifying agent, 250kg of carbamide, 180kg of calcium formate and 20kg of adjusting solidification agent into 700kg of water; fully stirring for 0.5-1.0 hour at 50 DEG C-60 DEG C to prepare a mixture No.2; and keeping the temperature of the mixture No.1 at 50 DEG C-60 DEG C, slowly pouring the mixture No.2 into the No.1 mixture while stirring; fully stirring for 0.5-1.5 hours to obtain the composite concrete grinding-assistant reinforcing agent which is brown liquid and hardly precipitates. The invention has the advantages of favorable stability performance, no influence on cementcondensation time, electricity saving, chlorine free, enhancement, simple use, low doping content, small investment and the like, improves output table yield of the cement by 15 percent to 30 percentand improves the age strength of the cement.