The methylol groups introduced to hexa aminocyclostriphosphazene(HATP) by the reaction with formaldehyde were analyzed quantitatively by the iodin method and the sodium sulfite method to observe the time dependence. Also the effects of temperature, HATP concentration and the molar ratio of formaldehyde to HATP were investigated. The reaction of amino group of HATP with formaldehyde was studied kinetically and activation energy was calculated from the data. The rate of methylolation increased as the temperature and molar ratio of formaldehyde to HATP and the concentration of HATP were high but the total number of methylol group attached to HATP at gel point were vice versa. The activation energy of the methylolation were found to be 12.157 kcal/mole from K1 (E1) and 10.652 kcal/mole from K2 (E2), respectively.