Chemical vapor deposition (CVD) at high temperature and pressure in a unique bell-jar reactor has been widely applied for high-pure polysilicon production using trichlorosilane (TCS) as a precursor. Silane is an alternative to TCS and used for ultrapure polysilicon. Nevertheless, silane is so reactive that results in significant homogeneous nucleated fines which lead to low yield and quality of crystalline silicon product. In this paper, we aimed to minimize the homogeneous nucleation by modulating flow pattern and temperature field in reactor. A novel bell-jar reactor with cooling jacket for each rod was modeled and simulated based on a three-dimensional CFD model. Contribution of homogeneous nucleation to rod growth on a basis of kinetic theory was included. The result showed that, in the novel reactor, the fresh feed was restricted in channels between cooling jacket and rod in which the favorable temperature and velocity profiles were achieved, and the gas phase near the rod was cooled so that the homogeneous nucleation was suppressed. In addition, the silane pyrolysis with simultaneous homogeneous nucleation and heterogeneous deposition was calculated and analyzed for various combinations of operating conditions.