The application of nuclear magnetic resonance cryoporometry（NMRC）for cementitious materials was analyzed. The constant in GibbsThomson equation that described the relationship between decrease value of ice melt point and pore size was obtained via measuring some mesoporous molecular sieve with certain pore size. The constant was then used to analyze the white cement samples with different mW/mC at different ages, and the possible error was discussed. The preliminary result shows that NMRC can give more details of pore size distribution of white cement samples than other methods, such as the volume of close micropore.