The main error source effecting the mechanical precision of the machine spindle is the structural thermal deformation under temperature variation. So, we focused on temperature variation investigate of spindle in experiment approach. A magnetic loading device has been used for the measurement, which have a more compact stator and shorter axis length. Meanwhile, the FEM 3D analysis of the compact magnetic loader has been presented. By using this contactless loader, the temperature variation when spindles are rotating under different loads have been monitored and recorded. Experiment results show that the radial load has increased the temperature of spindle, but the higher speed directly weakened this influence. Furthermore, this experiment approach is verified and proved to be suitable for spindle tests.