Based on the two-regime theory of Davis

a complete motion differential equation for a single oscillating microparticle in an electrodynamic balance (EDB) has been put forward by introducing Oseen’s formula and inhomogeneous term and solved numerically by using the classic Runge-Kutta method in this paper. The fact that there exists a transitional regime

in which the charged particle can be in steady damped oscillation

has firstly been demonstrated by theoretical method. By virtue of the simulated trajectories

a three-regime state curve (δ-β)

which is different from Davis theory

has been delineated and the theoretical foundation of EDB research on microparticle oscillation has further been built up.And the above-mentioned theoretical results have been verified experimentally hereby.