Microwave detection technology is applicable in the field of winter bamboo shoots detection because of its high efficiency, non-invasiveness, low cost and other characteristics. In order to clarify the optimal center frequency of microwave signals in the process of winter bamboo shoots detection, an electromagnetism coupling model of winter bamboo shoots-soil was constructed, and the change rule of microwave detection frequency was researched. Firstly, the E5080B ENA vector network analyzer was used to test the dielectric properties of winter bamboo shoots and soil, and analyze the influence of signal frequency on the dielectric properties of winter bamboo shoots and soil with different water content. At the same time, ANSYS HFSS 15.0 simulation software was used to design a back-cavity dish antenna with an operating frequency in the range of 1.5 ~ 2.0 GHz. The winter bamboo shoots-soil electromagnetism coupling model was established based on the data of dielectric constants corresponding to soils with different water contents in this frequency range. Based on this model, simulation and comparison tests were carried out for winter bamboo shoots with a water content of 86.82% and soil with water contents of 17%, 20%, 23%, 26%, and 29%, respectively, to investigate the response characteristics of the S?? parameter with the variation of dielectric. The results showed that as the soil water content became larger, the S?? parameter became smaller and the signal loss became larger, the winter bamboo shoots became more capable of absorbing the energy signals transmitted by the antenna, and it can distinguish the return signals with and without the winter bamboo shoots more efficiently;at the same time, since the antenna had the highest transmission loss at the frequency of 1.6 GHz, the optimal center frequency was 1.6 GHz.