In the downhole operation, string channeling are covert and unexpected, which can easily lead to well control accidents, while there are few studies on the causes of the currentdownhole operationin string channeling analysis and response measures.Through analysis on the causes of the string channeling via typical cases in the field, it is concluded that the main reasons for the occurrence of the string channeling in different downhole operation aregas cut, piston effect and circulating pressure difference. Combined with the above reasons, the anti-channeling short section, top gland type anti-channeling and preloaded hydraulic anti-channeling device are provided to prevent string channeling. The mechanism and application scope of the three kinds of emergency equipments are analyzed. The above conclusions and equipment are applied to well Y-1 wells for analysis.The results show thatthe calculation formula can be used to predict the occurrence of string channeling accidents andemergency equipment can effectively control the string channeling.The formula and emergency equipment shall be further promoted and optimized in the next step.