This paper reports a method of logarithmic straight lines of electron spin resonance (ESR) spectra which has been used to detect the phase transition temperature of Zns:Mn. This experimental analysis gave satisfactory results in the study on influence of trace dope on the phase transition temperature of ZnS crystallite. The difficulty that experiments of X-ray diffraction can not distinguish the phase transition temperatures of ZnS with Mn2+ concentration in the range of 10-3-10-6 gram/gram, had been surmounted.