Provided are uses of the combination of a µ opioid receptor (MOR) agonistand a .kappa.opioid receptor (KOR) agonist in the preparation of drugs for relieving and/ortreating pain.The MOR agonist is selected from the compound represented in formula (I), or atautomer,mesomer, racemate, enantiomer or diastereomer thereof, or a mixture thereof,or apharmaceutically acceptable salt thereof. Also provided is a pharmaceuticalcompositioncontaining the MOR agonist and the KOR agonist.(see above formula)