The invention discloses an ultraviolet index correction method, which comprises the following steps that: obtaining sensing data from an ultraviolet sensor, and substituting the sensing data into a computational formula to obtain an ultraviolet index; when the ultraviolet index calculated by the sensing data exceeds a first threshold value, according to the computational formula and the first threshold value, obtaining a gain parameter, and according to the gain parameter, carrying out gain calculation on the ultraviolet index; judging whether the difference value of the current ultraviolet index and a previous ultraviolet index exceeds a second threshold value or not, if the difference value of the ultraviolet indexes measured by a plurality of measurement points behind the current ultraviolet index and the previous ultraviolet index does not continuously exceed the second numerical value, replacing the index which exceeds the second threshold value with the previous index; correctingthe ultraviolet index which is smaller than a third threshold value into zero; and according to the calculated ultraviolet index, correcting the gain parameter of the computational formula of the ultraviolet sensor.