Abstract: Well G68-16 is the first test well for ?206.4 mm slim hole in the south of Jingbian gas field block. In line with complex formation characteristics in this block and combining drilling characteristics of G68-16 slim hole, optimizing bottom hole assembly (BHA), drill bit and screw model, technical measures like optimizing the parameters, drilling fluid maintenance and prevention of downhole troubles were applied, The well was successfully drilled with four runs during the second section and four runs for reaming; reaming down took 16 days due to handling downhole trouble in later drilling stage; the average penetration rate was increased by 19% compared with the original ?215.9 mm hole. The test is very successful, has accumulated experience for further slim hole test drilling in this block and provides favorable technical reference for increasing drilling rate.