The electrohydrodynamic phenomena caused by atmospheric has been studied for many years aiming for active flow control applications. Especially, Surface dielectric barrier discharge (DBD) type plasma actuator gets much attention because it has simple and thin structure, and therefore easy to be installed on any aerodynamic surfaces. Although it is attractive flow control actuator, for practical applications, it is required to optimize its configuration and driving parameters for maximizing the performance, and furthermore, to find applications in which high flow control gain can be obtained even by weak electrohydrodynamic force of plasma actuators. For this purpose, it is important to well understand the physics involved in the EHD force generation, and plasma numerical simulation is powerful tool for analysis. In this presentation, numerical simulation technique is introduced focusing on the EHD force generation. Three topics are included in the presentation. The first topic is the effects of plasma chemical reaction model on the EHD force generation. The second topic is the validation of three-fluid plasma numerical modeling, and the final topic is the three-dimensional simulation of surface dielectric barrier discharge.