A novel rheological measuring apparatus was designed, which introduced an additional sinusoidal vibration in parallel on the extruding direction of melt polymer in this article. Melt rheology of polypropylene filled uncoated CaCO 3 particles in 3 and 20 %wt amounts of filler during capillary melt-extrusion was investigated, respectively. A mathematical model of melt polymer under the action of vibration was set up. The effects of vibration parameters on rheological behaviors were studied. The apparent viscosity of filled system decreased remarkably with the increasing vibration frequency and amplitude. The apparent viscosity reached to minimum value when the vibration frequency was 8 Hz. POLYM. COMPOS., 36:630-634, 2015.