Abstract: The turning temperature has an important influence on the surface quality of workpiece and the service life of cutting tool. An open-type heat sink internal cooling tool was proposed in this study, and its structural strength was analyzed firstly by calculating the cutting force and heat flux density on the rake face under the practical machining process parameters. Based on the established thermal-flow-solid coupling temperature field model, the temperature field distribution of the tool under the heat steady-state condition was then obtained. Furthermore, the influence of the number of heatsink in the blade coolant flow channel on the thermal conductivity of the tool was studied.Comparisons of the thermal conductivity between the open-type internal cooling tool with heat sinks and other internal cooling tools under the same heat source conditions were conducted. The results show that with the blade material of cemented carbide YT5, the tool had the best cooling effect (maximum cutting temperature was 187.1 ℃), when 6 heat sinks were applied under the heat flow density 10 W/mm². The maximum cutting temperature of the open-type internal cooling tool with 6 heat sinks was reduced by 12.1 ℃ by comparing to that of other internal cooling tools.