In this article, the chalcogenide slot waveguide is theoretically studied, and the highest power confinement factors of the slot region and the cladding region are obtained to be 36.3% and 56.7%, respectively. A high-sensitivity chalcogenide slot microring resonator sensor is designed and fabricated by electron-beam lithography and dry etching. The structure increases the sensitivity of the sensor compared with the conventional evanescent field waveguide sensor. The cavity has achieved a quality factor of 1 × 104 by fitting the resonant peaks with the Lorentzian profile, one of the highest quality factors reported for chalcogenide slot microring resonators. The sensor sensitivity is measured to be 471 nm/RIU, which leads to an intrinsic limit of detection of 3.3 × 10--4 RIU.