It was the Thai teenager's first match since she won the women's singles title at the World Championships in Guangzhou in August.
Ratchanok, who is seeded second in Denmark, was sidelined with a back injury forcing her to skip a couple of tournaments.
The 18-year-old is trying to climb up the Super Series rankings to be eligible for the lucrative finals in Malaysia in December. She is currently 12th and must be in the top eight for a ticket to the Super Series Finals.
Meanwhile, eighth seed Boonsak Ponsana, Thailand's top male player, was eliminated by India's Ajay Jayaram who needed just about 30 minutes to win 21-11, 21-14.