A data hashing method, a data processing method, and a data processing system using a similarity-based hashing (SBH) algorithm in which the same hash value is calculated for the same data and the more similar data, the smaller difference in the generated hash values. The data hashing method includes receiving computerized data, and generating a hash value of the computerized data using the SBH algorithm in which two data are the same if calculated hash values are the same and two data are similar if the difference of calculated hash values is small, wherein a search, comparison, and classification of data may be quickly processed within a time complexity of O(1) or O(n) since the similarity/closeness of data content are quantified by component values for each of the respective corresponding generated hash values.