The sensitivity study of propellants has been receiving heightened attentions from a lot of investigators. These propellants based on nitrocellulose are sensitive to accidental stimuli that result in catastrophic accidents. Thus energetic thermoplastic elastomers have been used as binders to replace some nitrocellulose to prepare insensitive high energy propellants. However, some defects are presented in the application of these binders. Based on the reason above, a novel binder named as step ladder-like nitrocellulose was synthesized by isophorone diisocyanate reacting with free hydroxyl groups of nitrocellulose first, and then reacting with polyethylene glycol. The reaction product was characterized by FT-IR, XRD, SEM, TGA, DSC and sensitivity tests. Results show that step ladder-like nitrocellulose is successfully synthesized from nitrocellulose, and it has a quasi-spherical shape and regular crystal structure. Furthermore, the thermal weight loss course of step ladder-like nitrocellulose is relatively gentle in the range of 175-450 degrees C and its mechanical sensitivity is less than that of raw nitrocellulose.