The Office of Basic Education Commission (Obec) is developing an online platform to assess and improve the English proficiency of Thai teachers nationwide.
Obec secretary-general Amporn Pinasa said the new standard will be based on the Common European Framework of Reference for Language (CEFR).
The standard for describing language ability consists of six different levels of performance ranging from A1 for beginners up to C2 for those who have mastered the language.
"The Education Minister, Nataphol Teepsuwan, has a policy to improve the English and digital skills of teachers across the country, so they can catch up with a fast-changing world," Mr Amporn said.
"In order to do so, we need to assess them first. We want to know how good or bad they are before helping them to improve their skills."
Mr Amporn said Obec has set a target for English teachers to acquire at least level B2 of the CEFR and A2 for teachers who teach other subjects. If they are ranked lower than the target, they will have to attend training programmes via an online platform.
In 2018, an assessment by the Education Ministry and British Council Thailand found about 75% of 40,000 English teachers in Thailand were ranked at the A2 level in CEFR.
Mr Amporn also denied rumours on social media that Obec has ordered teachers in public schools to use Thai mixed with English words to help improve students' "language knowledge".
"I've never said that," he said. "It's a misunderstanding. We have plans to improve the English proficiency of our students, but not by teaching them words mixed with Thai."
Obec recently launched an intensive English programme requiring all students to study English for at least five hours a week.
Last year, Thailand dropped from 74th to 89th out of 100 countries in the English Proficiency Index conducted by the global education company EF Education First.
Thailand's English language proficiency scored only 419 out of 800 under the company's point scale, which is considered "very low".
The kingdom is ranked 7th in Southeast Asia, behind Singapore, the Philippines, Malaysia, Vietnam, Indonesia, Cambodia, and ahead of Myanmar.