The present invention relates to the technical field of emergency protective device, especially to a sensitive over-current protector. The sensitive over-current protector comprises a square housing,two pins symmetrically arranged in the square housing, a temperature-sensitive element, two symmetrically arranged moving contacts fixed on the temperature-sensitive element, fixed contacts fixed on the pins and correspondingly arranged with the moving contacts, a regulation screw and a spring arranged between the temperature-sensitive element and the square housing; one ends of the pins are fixedin the square housing, and the other ends of the fins are extended out of the square housing; the center position of the temperature-sensitive element has quincuncial holes, and the regulation screwpasses through the center position of the quincuncial holes and is in screw thread fixing with the square housing; and the spring is sleeved at the external portion of the regulation screw. The sensitive over-current protector is compact in structure, convenient to install and high in sensitivity.