Abstract: SAW-based real time chirp z transformation processor is widely accepted as one of new supporting techniques for spectrum analysis in radar, communication, electronic warfare and radio telescope. However, a critical issue for a practical system is a dependence of frequency determination, which is the fundamental function of the processer, upon the temperature at which SAW chirp dalay lines operate. A correct understanding of the temperature behaviour of the processor will pave the way for system design and temperature compensation. As we know, so far no satisfactory analysis theory has been established. In this paper, an analytic expression for analysing the variation of the determined frequency with the temperature is introduced to M-C configuration of the processor, which is deduced from a time scale principle. This expression indicates that the variation is not only dependent on time-delayed temperature coefficient of device substrate, but is also a function of device parameters and operation frequencies. Furthermore, by means of our theory, a reasonable explanation could be given to the discrepency which appeared between the experiments and the theory done by Claude Lardat of Thomson CSF.