Abstract: Cationic konjac glucomannan(CKGM) was prepared by etherifying konjac glucomannan (KGM) with 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (HAT). The effects of reaction temperature, reaction time, and the amounts of NaOH and HAT on the zeta potential of CKGM were studied. Meanwhile, the functional properties of the resultant CKGM and its electrostatic interaction with soybean protein isolate (SPI) were investigated as well. The results indicated that the zeta potential of CKGM reached the maximum of 36.0 mV when the reaction temperature was 55 ℃, the reaction time was 1.5 h, the NaOH to KGM mass ratio was 2:1, and the HAT to KGM mass ratio was 2:1. Compared with native KGM, the solubility and emulsification ability of CKGM were significantly improved and their maximum values of 78.0% and 22.7% occurred in CKGMs of zeta potential 36.0 mV and 23.3 mV respectively. FTIR analysis confirmed that the -CN group was successfully introduced into KGM under the optimized conditions, and SEM observation revealed that the modification reduced the size and wrinkle the surface of the CKGM particles. CKGM could associate with SPI through electrostatic interaction and the greatest interaction occurred in CKGM with zeta potential 36.0 mV. Therefore, CKGM obtained by HAT modification has improved functional properties and can interact with oppositely charged polyelectrolyte, which is expected to gain wide applications in the food industry as a novel polyelectrolyte.