The invention discloses a testing method for heat locating errors of a linear shaft of a vertical machining center. The method comprises the steps that locating errors, namely, geometric errors, of measuring points of the linear shaft of the vertical machining center at the initial moment are firstly measured, then locating errors of the measuring points of the linear shaft of the vertical machining center at any moment are measured, conditions are not changed in the two measuring processes, finally data of the two times are subjected to differencing, and the heat locating errors of the measuring points of the linear shaft of the vertical machining center at any moment are obtained. Therefore, the influence of geometric errors of components of a machine tool on heat locating error measurement is avoided, and the accuracy degree of measuring results is increased. According to the method, the on-machine testing requirement of the heat locating errors of the linear shaft can be fast and efficiently met, the influence of the geometric errors of the components of the machine tool on heat locating error measurement is avoided, the deviation problems caused by displacement sensor or standard part using, clamping, alignment and fixing are avoided, and the accuracy degree of the measuring results is increased.