The invention discloses a time series data granularity uniform conversion method for line fault prediction, and mainly relates to a time span selection principle of line fault multi-granularity time series data and a granularity standardization method of line fault time series data. The time span selection principle determines the time range of multi-granularity data, and decides the data input of the time granularity standardization method. The trend judgment method presented by the invention accurately describes the fluctuation degree and change trend of each attribute sequence with time, and better ensures the integrity of original data features.