For the detection and identification of abnormal nodular tissues on the body surface, a microwave sensor structure loaded with a spiral resonator is proposed in this paper, a sensor simulation model is established using HFSS software, the structural parameters are optimized, and the actual sensor is fabricated. The S21 parameters of the tissue were obtained when nodules appeared by simulation, and the characteristic relationship between the difference of S21 parameters with position was analyzed and tested experimentally. The results showed that when nodules were present in normal tissues, the curve of S21 parameter difference with position change had obvious inverted bimodal characteristics, and the extreme value of S21 parameter difference appeared when the sensor was directly above the nodules, which was easy to identify the position of nodules. It provides an objective detection tool for the identification of abnormal nodular tissues on the body surface.