We studied high-pressure reaction of solid cyanamide in a diamond anvil cell up to a pressure of 21.7 GPa. The results of in situ high-pressure Raman spectroscopy and angle-dispersive X-ray diffraction experiments indicated the occurrence of pressure-induced oligomerization in cyanamide over 13 GPa. The Raman, NMR, and UV absorption spectra of recovered samples confirmed that the chemical reaction was irreversible and that the high-pressure products contained C=N bonds. Subsequently, results of kinetic studies showed the relation between pressure and the reaction rate. Meanwhile dependence of activation volume with pressure indicated that the steric factors affected the reaction. Additionally, the increase in the amount of CC bonds of recovered samples was attributed to the change of reactive sites of adjacent C N groups. These results suggest that the application of pressure can tune both the reactive sites and the reaction rate to affect oligomerization and even other chemical reactions.