SiO₂automatic analy zer FIA -33 is a kind of intellectualized water quality analy zer on-line, which adopts the advanced floating injection technology, solid luminescence lamp-house optical fiber technology and the modern computer technology.It triumphantly realizes the speedy real time inspection on-line of the SiO₂ content in the boiler water (steam).This disquistion expatiates on the characteristic of the SiO₂ automatic analyzer, and analy ses the work flow and principles.It summarizes the experience of the practice during these years at the end.