Abstract: An interchangeable lock core includes a main body, an operative ring, and a core body. The main body includes upper and lower sections, the upper section having two sides and a plurality of first holes each for receiving a driver and a spring therein, and the lower section having a first bore extending in a longitudinal axis thereof and a transverse reception hole in a mediate section thereof. The reception hole extends upwardly into the upper section and defines first and second operative edges respectively at two sides of the upper section. A blind hole is defined in the upper section and communicates with the reception hole for receiving a second spring and a ball therein. The operative ring is received in the reception hole of the lower section of the main body and includes a second bore in alignment with the first bore and an extension which projects outwardly from an outer periphery thereof and extends along an arc thereof.