In order to solve the problem of slow setting and hardening of styrene butadiene copolymer/cement composite cementitious material, zeolite was used as set conditioning material. The effect of zeolite on the setting time and early strength of the composite cementitious material was discussed. The mechanism of zeolite accelerating the setting and hardening process was also analyzed from the point of hydration heat evolution rate and hydration products. The results show that zeolite can accelerate hydration of the composite cementitious material. By promoting the hydration of C3A and C3S, zeolite shortens the induction period, increases the maximum hydration heat evolution rate and promotes the generation of AFt and Ca(OH)2. Thus, the setting and hardening process of the composite cementitious material is accelerated, the setting time is shortened and the early strength is improved.