The invention provides a power grid state similarity quantitative analyzing method based on locality sensitive hashing. The method comprises the following steps: power grid state information is read, power grid key information is counted, and key information is formed into signature vectors representing power grid states; angles among the signature vectors are computed; and power grid state similarity is judged. The method is applicable to the locality sensitive hashing (LSH in short) technology of an electrical power system. Power grid original state data are converted into the corresponding signature vectors, and the power grid states of corresponding moments are expressed via the signature vectors. On the aforementioned basis, computation of degree of similarity of the power grid states is realized by utilizing similarity of the signature vectors. Large data of power grid state information are converted into the signature vectors of small data so that analysis of overall data is avoided.