At the time of its disbandment in 2021, it was the largest teachers' organisation in Hong Kong with over 95,000 members, representing over 90 per cent of the profession.

[5] On 12 December 1980, the British journalist Duncan Campbell revealed the existence of the Standing Committee on Pressure Groups (SCOPG) in an article in the New Statesman.

The SCOPG was set up by the Hong Kong government to increase its control over the opposition groups under secret surveillance; the PTU appeared on the list.

[6] The PTU has held the Education functional constituency in the Legislative Council of Hong Kong since its creation in 1985.

In the same year, the PTU initiated the Joint Committee on the Promotion of Democratic Government (JCPDG) which demanded the constitutional reform for the direct election in 1987.

In the first LegCo direct election in 1991, Szeto Wah contested in Kowloon East and Cheung Man-kwong, the PTU president and also United Democrats member, ran for the Teaching constituency.

In 1994, in response to pressure from the PTU, the Education Department agreed to subsidise the salaries of teachers in all non-profit making kindergartens.

On 31 July 2021, Chinese state media People's Daily and Xinhua News Agency published articles accusing the PTU of "encouraging anti-China activities that mess up Hong Kong", calling it a "poisonous tumour" that "must be eradicated".