Abstract: The CNC machining process inevitably experiences thermal deformation of the spindle caused by temperature, which brings thermal errors to the machining of parts and affects the surface accuracy of parts. This article uses an infrared thermometer to explore the sources of thermal errors in CNC machining centers, and explores the distribution of spindle temperature field and machining errors of parts without and with cutting fluid; The experimental results show that the spindle speed of a CNC machine tool is 6000 r/min, and the spindle can reach a constant temperature state after heating up for about 18 minutes. When the cutting depth is 1 mm, the machining error distribution is 0.01~0.03 mm with cutting fluid, and 0.03~0.06 mm without cutting fluid. Cutting fluid can significantly reduce the impact of spindle thermal error on mechanical machining accuracy. This study has practical guiding significance for CNC machining.