Classical swine fever virus (CSFV) is the causative agent of Classical swine fever which is a highly contagious disease affecting swine and resulting in severe economic losses. In this study, we developed reverse transcription loopmediated isothermal amplification (RT-LAMP) assay targeting the 5'UTR gene for the detection of CSFV. This amplification method can be obtained in 1 h under isothermal conditions (65°C) employing a set of six specific primers mixtures. Amplification product was visualized by using hydroxynaphthol blue (HNB) dye and agarose gel electrophoresis. The sensitivity was 100 copy numbers. No cross-reactivity related to Japanese encephalitis virus (JEV) and porcine reproductive and respiratory syndrome virus (PR-RSV) was demonstrated. The results demonstrated that the RT-LAMP assay is a useful tool for the rapid and sensitive for CSFV detection in swine.