This study is focused on a water-born thermo-sensitive material composition based on an infrared (IR)-sensitive (830nm) polymer nano-particles and the potentiality in preparation of environment-friendly CTP plate. Polymer nano-particles containing IR-absorbing dye (IR nano-particles) were prepared through soapless emulsion polymerization in the presence of active emulsifier and a redox initiation system. A water soluble polymer, poly (N-hydroxymethyl acrylamide) (PHMA), was used as the binder resin. An IR laser-imageable coating was prepared with the above materials as the main components. Upon laser exposure, the IR dye of the polymer particles absorbed IR energy and produced high temperature, leading the particles to be fused and causing great changes in both surface morphology and inner structure of the coating. As a result, the exposed areas were no longer water-soluble or water-dispersible, whereas the unexposed areas remained unchanged and were still soluble or dispersible in water. When developing with water, negative images would be obtained.