A expandable multi-physiological parameter monitoring ring, comprising a microprocessor module (1) and an internal sensor module (3) connected to the microprocessor module (1), and further comprising an external module interface (4) detachably connected to the microprocessor module (1) and used for connecting an external sensor module (5). The microprocessor module (1) is configured to: when the external module interface (4) is connected to the external sensor module (5), obtain measurement signals from the external sensor module (5) and the internal sensor module (3), and process the measurement signals to obtain a difference between a measurement signal of the external sensor module (5) and a measurement signal of the internal sensor module (3)； and when the external module interface (4) is not connected to the external sensor module (5), calibrate, according to the difference, a physiological parameter obtained by the internal sensor module (3). The monitoring ring can improve accuracy of physiological parameter measurement at a fingertip, and can implement low load, portability, and comfort.
