In this study, the pore structure of magnesium potassium phosphate cement paste is investigated using mercury intrusion porosimetry. Several mix proportions, obtained by changing the magnesia-to-phosphate molar ratio (. M/. P) and the water-to-cement mass ratio (. W/. C) of the material, are involved. It is found that lower W/. C and longer material age make the porosity lower and the pore structure finer. When the W/. C is kept constant, both porosity and critical pore diameter are not monotonic functions of M/. P, but the M/. P of 6 gives the lowest porosity and the smallest critical pore diameter. Also, the M/. P of 6 shows the highest compressive strength and the lowest intrinsic permeability. Based on the experimental results, empirical models describing the relations between the properties and pore structure parameters (porosity ϕ and critical pore diameter d) of MKPC paste are developed. The compressive strength is inversely proportional to ϕ, and the intrinsic permeability is directly proportional to dc2ϕ.