Abstract: In order to further enhance the penetration rate of slim holes in the Southern Sulige Block and reduce the development cost, technical research on the one-trip drilling technology of the second-spud section has been carried out. For this purpose, by means of bit modification, the bit teeth arrangement and streamline designs were optimized to enhance the bit stability and abrasion resistance. The positive displacement motor (PDM) design was optimized to prolong the service life and output power of PDM. The drilling parameters were optimized to realize an aggressive drilling and improve the rock breaking efficiency of bit. The BHA was optimized and the well trajectory was reasonably adjusted to ensure that the drilling of the long hold section and drop section could be fulfilled in one trip. Tests of one-trip technology of the second-spud section were carried out on two slim holes at SN00XX platform. Among these wells, Well SN00XX-02 achieved one-trip drilling of the second-spud section with the PDM. Well SN00XX-04 achieved one-trip drilling of both the PDM and the bit in the second-spud section. The technology of one-trip drilling was successfully applied in other two wells, and the drilling cycles were shortened by 7.6%. The research results showed that one-trip drilling technology could effectively implemented in the second-spud section, with remarkable improved penetration rate, which provided a technical support for the follow-up rapid drilling of slim-holes in the Southern Sulige Block.