This instrument utilizes a negative pulse of specific voltage amplitude applied between the polarized electrode and the reference electrode to selectively target ozone for participation in the reaction, causing it to undergo an electrochemical reaction at the cathode of the electrode, thereby generating a current signal proportional to the ozone concentration. The instrument calculates the ozone concentration by collecting and analyzing the current signal. As a result, this instrument features strong selectivity; no replacement parts; minimal maintenance; long electrode lifespan; and high reliability.