The extended approximate analysis on the electrostatic potential distribution around a spherical colloidal particle in asymmetric electrolytes has been performed. This analysis originated from the accurate perturbed scheme of Ohshima et al.[8] pertaining to the spherical poisson-Boltzmann equation for symmetric electrolytes. The advantage of this approach lies in the analytic expression for a flat plate very near the particle surface as well as its ability to yield the correct asymptotic behavior at distances far from th particle. The second order approximate solution for the surface charge density as functions of A(=ka) and surface potential has also been obtained from the similar method of perturbations to the Poisson-Boltzmann equation in spherical and cylindrical coordinates and compared with the exact numerical results. This study herein consisted of an analysis combined with experimental investigations to examine the changes in surface charge density and surface potential due to the variations of particle size and ionic concentration. Over an ionic strength range of 0.1 to 10mA, the evealuated surface potentials were found to lie in the ranges of about 60-230mV, and 72-149mV for three different sizes of polystyrene laties as a model spherical particle and the xamhen gum anionic polyelectrolyte as a cylindrical partcle, Indeed, the surface potential value increased as the particle size increassed, but decreased as the ionic concentration increased.