Rails are important facilities related to safe running of trains. When buckling occurs due to thermal expansion, serious safety accidents such as train derailment can occur. Currently, operating organizations are building expensive temperature monitoring systems and automatic watering devices. However, they have limitations for universalization due to their costs. Recently, long-term rail temperature reduction effect has been demonstrated by applying thermal insulation paint to rail surface. However, when coating the rail surface with paint, it increases the difficulty of detecting defects through nondestructive testing, which is one of the important elements of rail maintenance. To solve this problem, previous studies have proposed a detachable thermal insulation fabric by coating the surface of a fabric with thermal insulation paint and attaching a magnetic material. In this study, effect of thermal insulation performance according to manufacturing method was analyzed to derive the optimal performance of the previously developed thermal insulation fabric. Experiment results confirmed that paint weight increased when the roller method was used compared to the spray method with temperature reduction performance improved. Finally, the most efficient and optimal paint weight ratio was derived when the roller method was applied.