This study was conducted to investigate the possibility of emulsifiable concentrate(EC) development and the stability and acaricidal activity of the formulated emulsifiable concentrate. Cyhexatin could be formulated into 9% EC by using phenol as a cosolvent and E-ASC as an emulsifier. Cyhexatin EC was, stable in 0.5% moisture content, pH 4.5 and 7, but it was unstable in more than 1% moisture content and the alkaline condition of pH 9.5. The emulsion cyhexatin EC was unstable in hard water of pH 10. The acaricidal activity of 500 fold of 9% EC was shown to be as good as that of 27% wp of 1500 fold.