The invention discloses a desensitization method and device for electricity customer data, and a desensitization reduction method and device for electricity customer data. The desensitization method for electricity customer data comprises the steps: obtaining to-be-desensitized electricity customer coded data; according to a preset data desensitization seed value and the first preset segment length parameter, converting the electricity customer coded data into a first random mapping array by utilizing a random sorting function; dividing the electricity customer coded data into a plurality of sub-segments with preset lengths according to a first preset segment length parameter; and sequentially indexing the codes corresponding to each field of the electricity customer coded data in the first random mapping array, and obtaining the desensitized electricity customer coded data. The desensitization method and device provided by the invention have the characteristics of simplicity and highefficiency, can guarantee the uniqueness of the desensitized electricity customer data, can recover the electricity customer data before desensitization through the public parameters of the desensitization and reduction method, can be suitable for other data analysis actual scenes while the user privacy is protected, and can the data value.