The invention provides a correlation degree calculation method and device. The method comprises the following steps: calling power data of at least two electricity customers from a background database, and determining a target customer and at least one comparing customer from all the electricity customers, wherein the power data comprise customer information and customer electricity information; aiming at each comparing customer, calculating single-factor matching similarity according to comparing customer information and target customer information; meanwhile, calculating multi-factor compound similarity according to comparing customer electricity information and target customer electricity information; aiming at each comparing customer, calculating the correlation degree between the comparing customer and the target customer according to the single-factor matching similarity, the multi-factor compound similarity and respective weight values. Based on the method provided by the invention, correlation measurement is carried out on a lot of power data at the same time; meanwhile, the customer information and the electricity information are comprehensively calculated and the accuracy of calculation is also guaranteed.