Abstract: In the storage process, physical or chemical changes might happen for thermosetting resins, which have effects on the rheological characteristics of resin systems and influence the processability. By means of parallel plates the effects of storage time on rheological properties of resin systems were studied for several typical thermosetting resin systems used in the hot press process. The reasons for the change of rheological characteristics were investigated with differential scanning calorimetry, infrared spectrometry and gel permeation chromatography. The influence of storage time on the processing property of resin systems was analyzed using the fluidity. The results show that the storage characteristics of resin systems are determined by the curing reaction of the resin system and the storage characteristic of addition agents in resin system. These results provide some important experimental information to the estimation and optimization of hot press process parameters.