The present invention discloses a method for measuring the zeta potential at the cylinder's outer surface. In the measuring cell, the cylinder is held coaxially inside a reference tube and a given solution is forced to flow through the annular flow channel between the cylinder and the reference tube. The streaming potential induced by the flow forced with a hydraulic pressure drop is measured to determine the zeta potential, ζm, of the cylinder's outer surface by using the following Equation, E _ Δ ⁢ ⁢ P == - D μ ⁢ ⁢ k ⁢ ( ζ m + ζ ref 2 ) ⁢ F where D is the permittivity, ζref is the zeta potential of the reference tube, μ is the viscosity of the solution, k is the electric conductivity of the solution, and F is a correction factor for the electrokinetic model. Moreover, this invention also discloses a system for measuring the zeta potential of the cylinder's outer surface.