The characteristics of electroosmotic flow in a cylindrical microchannel with nonuniform zeta potential were investigated in this paper. The Poisson-Boltzmann equation and momentum equation were used to model the electrical double-layer field and the flow field. The numerical results show the distorted electroosmotic ve city profiles resulting from the axial variation of the zeta potential. Also, the influences of the unequal section size and the direction of the zeta potential change on the velocity profile, the induced pressure distribution, and the volumetric flow rate are discussed in this paper. The simulation results revealed possible effects of bioadhesion in microchannels on the electroosmotic flow in biochip devices.