Abstract: Safety joints are various in kind and different in structure, and rotating strings are mainly taken for the releasing operation. With the increase of horizontal well, high deviated well and combined strings, the complex wellbore structure and technical limitation of working string leads to low reliability and even failure of safety joint releasing operation. Therefore, sliding sleeve safety joint was designed and generated, and it can finish releasing operation by ball dropping and pressure building. The new method avoided the operations of dragging, pressing, and wrenching of string releasing, and fulfilled various complex operations from function and property points of view. The sliding sleeve safety joint has simple and appropriate structure design, with strong operability, and wide application region. The indoor and field tests proved the property stability and operational reliability of the sliding sleeve safety joint, so it could be applied further.