A method for extracting feature of signatures includes the following steps. Sense touch input of a handwritten signature by a user on a handwritten input unit. Generate associated with the user's touch input of the handwritten signature. Detect coordinates of each of touched points of the handwritten signature of the user according to the generated signals. Select feature points from the touched points. Obtain coordinates of the feature points of the handwritten signature. Combine the selected feature points and the coordinates thereof to obtain signature features of the handwritten signature of the user. And store the extracted signature features of the handwritten signature of the user in a storage unit. A signature feature extraction system using the method is also provided.