In order to simplify the coding process of the SAW sensor,a novel encoding method is proposed based on SAW resonators connecting SAW resonators with different center frequencies to different load impedance.The specific structure of the encoded sensor is designed and the equivalent circuit model is established.Two sensors consisted with SAW resonators of the center resonant frequency of 868 MHz and 915 MHz respectively,were simulated using the ADS simulation software.The results show that the center resonant frequency difference of the two SAW resonators with 1 pF external impedance and 4 pF external impedance reaches to 200 300 kHz. According to the simulation results,two different encoded sensors,one with no external impedance and another with 10 pF external impedance, were designed and tested.The measured resonant frequency difference can reach to 39.75 40.2 kHz. So the resonance frequencies of the two SAW resonators with different external impedance are different,and the sensor coding method based on the SAW resonator and the external impedance is feasible.