The compatibility of nitrocellulose/polyethylene glycol(NC/PEG) blended system with different mass ratio was studied by DSC and DMA. Results show that with increasing the content of NC in NC/PEG blended system, the melting point, crystallinity and entropy of crystallization of PEG decrease obviously. The value of interaction parameter χ1,2 of the blended component is negative, i.e. the blended system possesses the compatibility on thermodynamics. With increasing the content of NC, the glass transition temperature of the blended system shifts downwards. When the mass ratio of NC and PEG in the blended system is 1∶1, the blended system reveals a single glass transition temperature.