Sensors have been used in biological detection. The high sensitivity of the sensor chip has become a new research hotspot. Two-dimensional and three-dimensional coupling silicon nitride microcavity sensors are experimentally demonstrated based on the high sensitivity, low cost, and easy integration of the silicon nitride microcavity. The application of the integrated silicon nitride microcavity optical sensor chips in refractive index measurement is studied in detail. A quality factor of more than 16000 at a wavelength of 1550 nm can be obtained in two-dimensional structure and a quality factor of 4000 at a wavelength of 1550 nm can be obtained in three-dimensional structure. It is demonstrated that suspension structure can greatly improve the performance of the device.