Abstract: Accurate measurement of CPU chip's temperature is the important precondition for assuring the performance of microprocessor and for promoting the chip's reliability.On the basis of theoritical analysis of thermal effect of transistor parameters, a kind of high sensitive on-CPU-chip thermal sensor which is based on the thermal effect of transistor collector current is proposed.On the basis of theoritical analysis of hotspot's thermal field in CPU chip, a kind of high accurate on-CPU-chip thermal sensor array is proposed.Both proposals are proved by deduction and simulation.