Online monitoring system and method for stevioside purification process

The invention discloses a stevioside purification process on-line monitoring system and method, the on-line monitoring system comprises a solid content PID adjusting module, a detection module and a display alarm module, the solid content PID adjusting module comprises an industrial computer, a refractometer, a purified water storage tank, a self-priming pump, a control valve and a flowmeter; the detection module comprises a mixer, a flow cell, an optical fiber, a spectrometer and a light source; the display alarm module comprises an industrial computer and an alarm; the on-line monitoring method comprises the following steps: S1, controlling the solid content level to be 4.0% when a solution at a lower column opening of a resin column flows through a flow cell through a solid content PID (Proportion Integration Differentiation) adjusting module; s2, acquiring absorbance values A430 and A290 under the wavelength of 430 nm and the wavelength of 290 nm in real time by using a fiber optic spectrometer; and S3, m