In recent years, the small-diameter coring technology has been widely used in oil and gas exploration. Incidents often happen in the hole during drilling, such as frequent wellbore overcut, large displacement due to high deviation at the bottom of the hole, unstable drilling fluid performance. The small-diameter coring technique was used to drill the geological survey hole of Well Tongdi-1 for oil and gas, and it was successfully completed with all drilling indicators meeting the geological design requirements through optimizing drilling parameters, properly determining the drilling structure, and adopting effective measures to prevent hole deviation.