In this paper, employing reservoir simulation and mathematical analysis methods, considering typical heavy oil reservoir and fluid thermal properties, the heating and producing shape of thermal recovery with horizontal well for different heavy oil reservoirs including ordinary, extra and super heavy oil are investigated based on the modification of thermal recovery parameters of different viscosity. By introducing heating radius and producing radius and considering the coupling effect of temperature, pressure and oil saturation fields, a quantitative expression between heating radius/producing radius and oil viscosity, formation thickness is presented, so is the impact of oil viscosity on the heating radius. Results shows that for Cyclic Steam Stimulation, the producing radius of horizontal well is bigger than its heating radius for light oil, both of which, however, shrink with higher viscosity. Beyond a critical viscosity, where the heating radius equals to the producing radius, the heating radius of horizontal well would be bigger than its producing radius. More over, the critical viscosity shows tight relationship to the formation thickness.