The invention discloses a folding micro-strip line microwave biosensor with reference characteristics and relates to the technical field of microwave biomedical biosensors and specially relates to a novel microwave biosensor with reference characteristics and which can be used for detecting malignant melanoma and skin moisture content. The sensor utilizes the interaction of surface plasmons produced by microwaves on metal conductors with human skin tissue to detect the water content that distinguishes between normal and cancerous tissue or skin of a different nature. At the same time, the sensor uses a folded micro-strip line structure so that the test result is referable. The microwave biosensor uses the microwave frequency band of 5-13GHz, with small reflection, flat insertion loss, uniform phase and other characteristics suitable for the distinction between skin moisture content and malignant melanoma.