A temperature sensing system with simplified wiring comprises an in-core temperature sensing component and an out-of-core temperature-evaluation device. The out-of-core temperature-evaluation device provides a plurality of currents to the in-core temperature sensing module in a time-sharing manner. Corresponding to the plurality of currents, the in-core temperature sensing component generates a plurality of potentials to the out-of-core temperature-evaluation device. The out-of-core temperature-evaluation device evaluates a temperature data by performing a difference calculation on the plurality of potentials.