This paper analyzes geometrical approaches to optimize the fluid cooling circulation of motorized spindles. The spindle fluid cooling’s effectiveness, efficiency and influence on the machine’s precision are analyzed through observations of the stator temperature, pressure drop and thermal asymmetry, respectively. The observation is based on a validated coupled thermal/fluid mechanical simulation model. The widely used helix and meander shape stator cooling sleeves are primarily investigated. Additionally, a so-called S-meander shape was developed, which combines the advantages of the formerly mentioned sleeves. In order to understand the nonlinear thermal interactions properly, width and height of the cooling channels were varied separately and simultaneously. While keeping the flow rate identical, the average stator temper¬ature could be decreased by 2.3 K solely with geometrical optimizations. Interestingly, the motor temper¬ature is not continuously decreased by raising the fluid velocity through a reduction of the cooling channels size. For the helix and the S-meander, the temperature actually increases after passing a certain geometrical sweet spot. Additionally, this optimum is different for the helix, meander and S-meander cooling sleeve. The results imply that the geometrical optimization of fluid cooling channels in motorized spindles has a significant potential. Furthermore, the developed cooling sleeves are trans-ferable to any electric motor with fluid cooling.