When the metering codes acquired are directly used in electricity settlement， some errors maybe occur in the calculation of electric energy data. An efficient algorithm based on the time-sequence feature of electric energy data is proposed. Firstly， the lost data are automatically inserted and the incorrect data are corrected to assure the continuity and integrality of the sequence. Then， several techniques， i.e. returning to zero， changing meter， changing current transformer/potential transformer， distinguishing from bypass， are used to simplify the calculation of the electric energy data. Finally， the lost energy data are manually inserted and the unequal electric energy data are automatically distinguished to reduce the losing of the electric energy data and to verify the correctness of the electric energy counting. The method proposed is verified based on the electricity purchase management system in Hebei Province Power Company， and promising results are obtained.