Abstract: Traditional nuclear power plant（M310） adopts the bypass measurement method to measure the key safety parameter, i.e., the reactor coolant temperature, but this method cannot satisfy the requirement of the 3 rd generation nuclear power for the complicated process loop, large amount of connection on the main pipe and difficulty in the maintenance. This paper analyzes this physics phenomenon at first, and extracts a direct temperature detection scheme for the primary pipe which is suitable for HPR 1000 nuclear power plant, then verifies this scheme from the aspect of safety analysis. The result of the safety analysis verification indicates that the direct temperature detection techonoly for the primary pipe can be applied on HPR 1000 nuclear power plant with some special configuration.