Abstract: L well, with a designed well depth of 4650. 00m, is a wildcat in Zhongyuan oilfield. A drilling accident occurred at the depth of 4235. 60m and fishing operation failed, thus the well was sidetracked. Screw drill and wireline logging while drilling technologies were used and sidetracking operation was successfully accomplished. This paper details the operation process of deep sidetracking in this well.