Triethanolamine (TEA) is one of the main components of commonly used high efficiency grinding aids, but its grinding aid effect on steel slag mixed materials is single and costly. TA is obtained by modifying TEA with acrylic acid and comparing with TEA and blank group under the help of specific surface area, particle size distribution, SEM, XRD, FT-IR etc. to study the effect and action mechanism of the modifying agents on the particle dispersion and hydration properties of the steel slag mixed materials. The results show that the optimum molar ratio between TEA and acrylic acid is 1:1, and the optimum dosing is 0.03% of the mass of the mixed material. Under the best conditions, the specific surface area of the particles in the TA group is increased by 13.39% compared with the blank group, the compressive strength of the TA group mixed material 28 d, compared with the TEA group and the blank group, is increased by 9.26% and 11.32%. The modifying agent can increase the specific surface area of particles, improve particle gradation, promote C-S-H, C-A-H gel, CH crystals and calcium alumina generation, and improve early strength.