Zeta potential, setting time, structure reconstruction energy and dynamic yield stress, and static yield stress of cement ground limestone paste were determined by Zeta potential analyzer, VEKA instrument, rotary viscometer and static weighing instrument, and the action mechanisms of ground limestone were revealed in fresh cement paste under static and non static state. The results show that the main action of ground limestone in the fresh cement paste is related to its state. The setting time and absolute value of Zeta potential decrease, the induction is shortened, the acceleration period is advanced and heat discharge increases, and the static yield stress increases for cement paste with the ground limestone content(by mass, the same below) increasing during the resting state in which the action of nucleation of the ground limestone are dominant in the fresh cement paste. The absolute value of Zeta potential, dynamic yield stress and new building energy of the cement paste decrease with ground limestone content increasing during the non resting state in which the action of filling and gradation of the ground limestone are dominant in the fresh cement paste. If the fresh cement paste is only affected by slight disturbance, the growing rate of shear stress of the cement paste increases firstly and then decreases with the ground limestone content increasing, which achieves maximum while the ground limestone content is 20%.