Abstract: Phosphate cementitous material was considered as ideal rapid repairing materials owing to its excellent properties. However, its application was limited due to its shorter setting time and high cost. Phosphate-based rapid repairing material (MKPC) was prepared with desulfurization fly ash and tuff machine-made sand. Meanwhile the method of single-factor experimental design was adopted to study the effect of mix proportion on the properties of MKPC under high temperature conditions (30℃). The optimized mix proportion was determined by using value coefficient. The results show that the fluidity of MKPC demonstrates the parabola changes with M/P ratio, exponential decay with B/MPF ratio, linear growth with W/MPF ratio, exponential growth with S/MPF ratio, and exponential decay with CFB/MPF ratio. Secondly, the setting time of MKPC decreases linearly with the ratio of M/P, and increases with the ratio of B/MPF, W/MPF and CFB/MPF according to an exponential growth model. Thirdly, the mechanical property of MKPC about an hour declines linearly with the ratio of M/P, and improves with the ratio of B/MPF, W/MPF and CFB/MPF according to a parabola model. Finally, the optimized mix proportion is determined by using value coefficient, which meets the control range of the construction operability and early mechanical properties.