Abstract: The KG-300-2J flushing fluid purification circulation system using directional drilling in coal mine is developed. According to the characteristics of directional drilling construction and drilling cuttings, two-stage purification treatment mode including vibrating screen unit and centrifuge unit is adopted. We optimize the structure of vibrating screen unit and centrifuge unit to make it more suitable for the narrow space, transportation and explosion-proof requirements of coal mine. The industrial test shows that the purification circulation system of flushing fluid has stable performance and high reliability, the maximum solid content in the flushing fluid is less than 0.15%, the maximum particle size is less than 5 μm, the treatment capacity and purification accuracy meet the design requirements.