Aimed at resonant surface acoustic wave (SAW) sensor; the influences of side lobe rejection levels of three different window functions on SAW sensor are researched. Simulation results show that the performance of Kaiser window with high stop band attenuation up to -120.2 dB is more excellent than the other two. Meanwhile, SAW temperature sensor is designed using SiO2 crystal as the substrate material at LST cut and weighted inter digital transducer with Kaiser window. Test results present that the designed SAW temperature sensor has good consistency, temperature frequency characteristic and side lobe rejection. It can well meet the temperature monitoring application of power grid.