Abstract: With respect to the engineering practice issues in the dusty plasma domain, we studied the iteration method of solving charge-potential issue in hybrid model. In detail, the electron density obeys the Boltzmann law distribution, and the electrostatic potential is determined by Poisson's equation. The result indicates that the Newton iteration method is quite applicable for the simple case. But it is inapplicable to the complex case in engineer practice. The study validates that the parallel secant method is applicable for this complex case. The iteration can be convergent and stable when the value of down factor is within a certain range. At the same time, the convergence speed increases when the value of down factor increases.