Focusing on the detection of winding deformations within power transformers, this paper analyzed the characteristics and disadvantages of current short circuit impedance method and frequency response method for winding deformation detection. It was studied the fundamental and the wire connection method for sweep frequency shortcircuit impedance analysis (SFSCIA). Interlayer short circuit tests and interturn short circuit tests were conducted on a model transformer under different conditions to verify the validity of the SFSCIA. As a further validation, field tests were carried out on a 220 kV transformer at the substation based on SFSCIA. The SFSCIA method is a valuable testing scheme providing with more measurement data as assessment evidence of winding deformation.