OBJECTIVE To synthesize phytanetriol by epoxidation/ring-opening reaction under catalyst-free conditions using phytol as raw material, low concentration of hydrogen peroxide as oxidant, and formic acid as oxygen carrier. METHODS The effects of the molar ratios of formic acid and hydrogen peroxide to phytol, reaction temperature, and reaction time on the yield of phytanetriol were investigated using a single-factor test and verified by 3-batch reproducibility. The chromatographic purity and structure of phytanetriol were analyzed by gas-mass spectrometry, infrared spectroscopy, and nuclear magnetic resonance spectrometry. RESULTS The optimal conditions for the epoxidation reaction system were n(HCOOH):n(H₂O₂):n(phytol)=5∶1.3∶1, temperature 55 ℃, and reaction time 2 h. The optimal conditions for the ring-opening reaction system were pH=13, temperature 105 ℃, and reaction time 0.5 h. The phytanetriol synthesis process had a yield of 86.6% in the validated experiments. The chromatographic purity was 94.6%. CONCLUSION The synthesis process is stable and can produce phytanetriol with controllable quality and better purity than commercially available products.