The properties of error linear complexity of binary sequences with period of power of two are studied in this paper. Using the Games-Chan algorithm as main tool, accurate formulas of the minimum value k for which the k-error linear complexity is strictly less than the first and second critical error linear complexity are provided respectively. The properties of error linear complexity of binary sequences with period of power of two are studied in this paper. Using the Games-Chan algorithm as main tool, accurate formulas of the minimum value k for which the k-error linear complexity is strictly less than than the first and second critical error linear complexity are provided respectively.