A bad load data detection algorithm for power transmission and transformation equipment based on index of characteristic comprises the steps of calculating cluster validity index, determining optimal cluster number k, and clustering load curves by integration cluster algorithm to get characteristic curve Cp for each type. Difference zscore between actual load curve and characteristic curve of each type of load curves at each moment is calculated.Calculating difference zscore between actual load curve and characteristic curve of all load curves of all types at each moment. Smoothing each load curve by mobile median smoothing algorithm, subtracting original load curve by smoothing load curve to get error sequence en, calculating smoothing index mscore at each moment, detecting bad data, making iteration r=r+1, repeat Step 2-9 if r>M, or completing detection if r