The duo was joined in the last eight by mixed doubles pairs Dechapol Puavaranukroh/Sapsiree Taerattanachai and Supak Jomkoh/Supissara Paewsampran.
Sixth seed Ratchanok rallied to defeat fellow Thai Supanida Katethong 18-21, 21-12, 21-16 to qualify for the last eight of the World Tour Super 750 event, reports the Bangkok Post.
Up next for Ratchanok is world No.2 An Se-Young, who eased past Aya Ohori of Japan 21-12, 21-13.
Second seed An is chasing back-to-back victories after winning her home tournament - the Korea Open - on Sunday.
Men’s singles third seed Kunlavut defeated Kenta Nishimoto of Japan 21-18, 21-16.
Kunlavut will play fifth seed Jonatan Christie of Indonesia in the quarters today.
Second seeds Dechapol and Sapsiree also needed three games to defeat Dejan Ferdinansyah and Gloria Widjaja of Indonesia 21-16, 21-23, 21-12.
Dechapol and Sapsiree will meet sixth seeds Seo Seung-Jae and Chae Yu-Jung of South Korea in the last eight.
Another mixed doubles pair Supak and Supissara made it to the quarters after they beat Chan Peng Soon and Cheah Yee See of Malaysia 21-18, 19-21, 21-18.
Their next match will be against third seeds Yuta Watanabe and Ariya Higashino of Japan.
Women’s doubles stars Jongkolphan Kititharakul and Rawinda Prajongjai booked their last-eight spot with a 21-13, 21-19 win over Rui Hirokami and Yuna Kato of Japan.
However Aimsaard sisters - Benyapa and Nuntakarn - failed to advance after losing to fourth seeds Kim So-Yeon and Kong Hee-Yong of South Korea 9-21, 14-21.