With the16-bit MSP430 CPU as the core, full-scale measurements including ultra-low temperature are realized through the application of programmable gain analog-to-digital converter AD7715 connected to platinum resistance sensors. With the self-calibration capability of the AD7715, the drift and error of the device are removed. The problem of temperature accurate calculation is solved by the temperature-resistance function of different temperature segments. The experimental results show that the smart platinum resistance temperature transmitter can be directly matched with the platinum resistance sensors of different temperature segments. With the calibration parameter set of the sensor, the error caused by the universal sensor characteristics is eliminated and higher accuracy is obtained.