Objective To characterize the rheological properties of paper fiber and starch mixed material system using Discovery HR Series rotational rheometer, and to study the mixed uniformity of different formulations between the paper fiber and starch, as well as the effects of starch types, starch content and plasticizers ratios on the processing performance of the materials systems. Methods Biomass fiber materials were prepared using three-factor three-level orthogonal test method. Appropriate test parameters were chosen, and the plural viscosity-frequency curve and viscosity-shear rate curve were used as references, to discuss the rheological properties. Results Paper fiber and starch showed uniform dispersion after 15 min incubation at 85 ℃ in a water bath. The materials systems with different starch types, different starch content and different plasticizers ratios showed shear thinning properties. The order of factors affecting the viscosity of the materials systems was starch content