The Okinawa plate is located on the Western Pacific active belt, which was created by northwestward subducting of the Philippine Sea plate with respect to the Eurasian plate. The tectonic stress field and its dynamic mechanism demonstrates a very complicated pattern in this region. Using the pseudo 3-D finite element method, this paper numerically simulated the tectonic stress field in the Okinawa plate area, with the orientation and regime indicators from WSM2008 data base as principal constraints. Based on the simulated result we try to understand the state of lithosphere and to explore dynamic characteristics of the intraplate stress in this region. We thus estimated the effect of boundary forces on the intraplate stress field, and got some preliminary conclusions:① The asthenospheric static push forces mainly control the general spatial pattern of the intraplate stress field.② The evolution process of the Okinawa Trough, including the lithosphere thinning and moving up of the mantle flow in this region, also plays important role in constructing the stress pattern.③ The boundary forces acting along the Ryukyu subduction zone show segment dependence, with different force acting on different segment.