Stability of a conducting drop hanging from a nozzle in an electric field with corona discharge was examined theoretically for the first time. By this static model with linear stability analysis, stability of electrostatic Inkjet process was estimated. The basic equations, the augmented Young-Laplace equation for drop shape and the Poisson equation for electric field, were coupled and solved by the Finite Element Method. According to the initial condition of its shape, a drop is deformed and subject to corona discharge with the increment of non-dimensional electric field. It was found this static model was applicable to estimate the range of stable jetting and the existence of corona discharge reduces its stable jetting range.