the present invention provides a wireless temperature and humidity sensor and system , and measurement method . the wireless temperature and humidity sensor comprises a substrate , a feeding network , an antenna and surface acoustic wave resonators , wherein the surface acoustic wave resonators are fed by said feeding network through said antenna . said surface acoustic wave resonator comprises a reference resonator and measuring resonators . the resonant frequency difference between said reference resonator and said measuring resonators is used to modulate the temperature and / or humidity to be measured . said system can monitor both temperature and humidity simultaneously , or monitor humidity or temperature selectively . furthermore , frequency drift caused by aging of the sensor material and the connector is effectively suppressed by the differential modulation , thereby improving long - term stability of measurement and avoiding recalibration .