For the advancement of nucleic acid-related research, high-efficiency, low-cost synthesis of high-purity oligonucleotides is necessary. Herein, we introduced hydroxybenzotriazole (HOBt) activators on controlled pore glass resins to improve the efficiency of chain elongation (the synthesis efficiency increased from 48% without an activator to 92% with an activator). In particular, the use of the resin containing 6-trifluoromethyl HOBt with a linker of lauric acid and succinic acid significantly improved the synthesis efficiency for both DNA and RNA syntheses.