Abstract: Disclosed herein is a method of functionally coating a basalt fiber, including: coating a basalt fiber by passing the basalt fiber through an aqueous fluorine-based solution including 50˜60 wt % of polytetrafluoroethylene (PTFE), 2˜5 wt % of a nonionic surfactant and water at a passing speed of 1˜2 m/minute, the solution being maintained at a temperature of 20˜25° C.; drying the coated basalt fiber at a temperature of 80˜110° C.; heating the dried basalt fiber to a temperature of 180˜270° C.; and sintering the heated basalt fiber at a temperature of 360˜420° C. Further, disclosed herein is a method of functionally coating a basalt core yarn, including: preparing a basalt core yarn by winding a sub fiber around a basalt fiber, which is a main fiber, and then twisting the sub fiber and basalt fiber; coating the basalt core yarn by passing the prepared basalt core yarn through a coating solution including 35˜45 wt % of a phosphorus-based fire retardant, 50˜59.9 wt % of toluene, which is a solvent, and 0.