The numerical simulation of the flow and heat transfer in a portable thermostatic bath with spiral baffles to rotational viscometer calibration under different flow and structure parameters is developed. The temperature response characteristics of fluid in the rotational viscometer are investigated. SIMPLE algorithm is used to solve the pressurevelocity coupled governing equations employing QUICKtype scheme for variables discretization. Realizable kEpsilon Model is adopted for modelling turbulence. The numerical results show that when the number of spiral baffles in the water jacket increases, compared with the heating condition, Thermal stratification phenomena of fluid within the cup in cooling condition is enhanced, which is not conducive to meet the temperature uniformity requirements for viscosity liquid which to be measured. When the temperature difference between heating and cooling condition is same, for Installed different spiral baffles structure heating temperature response is basically the same as 0.24 ℃/min. Cooling temperature response decrease with the increasing number of spiral baffles, and the maximum difference is 0.036 ℃/min. With a fixed flow rate, temperature response of thermostatic bath increases with the increase of heat flux density. While just change flow rate, the temperature response of thermostatic bath with different structure is not obvious.