Abstract: Aiming at the synergistic effects between different kinds of cellulose ethers, hydroxyethyl cellulose (HEC) and carboxymethyl cellulose (CMC) mixed systems in aqueous medium were studied. Viscosity and oscillatory measurements were employed to monitor the parameters of apparent viscosity, rheology and viscoelasticity of HEC/CMC mixed systems with various mass mixing ratios, so as to analyze the mechanism of interactions between ionic and non-ionic cellulose ethers. The synergistic viscosity effects were observed in HEC/CMC mixed systems with thixotropy decreased, and the microscopic structures of mixed systems were further stabilized. The synergistic effects were more obviously revealed as <em<m</em<(HEC)∶<em<m</em<(CMC) approaching to 1∶1. When <em<m</em<(HEC)∶<em<m</em<(CMC) became 2∶1, the sharing electron field effect was formed. A relatively fragile network structure is presented as <em<m</em<(HEC)∶<em<m</em<(CMC) is 1∶2, due to the weaker interactions between HEC and CMC molecules.