The invention relates to a lateral coating type over-current protection element and a manufacturing method thereof. The over-current protection element comprises a positive temperature coefficient (PTC) chip, metal foil electrodes on both sides of the chip and two extraction electrodes, wherein the side face of the PTC chip is provided with a layer of airtight protective film. The manufacturing method comprises the following steps of: laminating the metal foil electrodes on both sides of the PTC chip which is subjected to compressed molding to form a composite chip; irradiating the composite chip, punching into small slices which meet the design requirements, welding nickel slices on all the two sides of the small pieces to serve as the extraction electrodes; sleeving a heat shrinkable pipe sleeve around the PTC chip; performing high-temperature heating treatment; and forming the airtight protective film on the side of the PTC chip to obtain the required over-current protection element. The over-current protection element has the advantages of ensuring low room temperature resistance by forming the airtight protective film on the side face of the PTC chip, along with high electric performance stability under the condition of high-temperature storage.