Liao's career in environmental protection began in 1976 at the University of Hong Kong when she supervised the first government-funded annual air monitoring project.
Another area of work was the management of toxic and hazardous materials (chemical and biological) used in the University, including the procurement, storage, delivery, use, pre-disposal treatment and final disposal of these substances.
At the same time she conducted large scale studies relating to workplace health and safety, hazard identification, risk assessment and environmental problems in a range of Hong Kong industries.
[citation needed] In 1988 Liao founded EHS Consultants Limited which provided a range of environmental services requiring specialist expertise.
Recent projects included the study on air quality in the Pearl River Delta, Toxic Substances and pollution in HK waters.
[7] Liao was named Secretary for the Environment, Transport and Works in August 2002 as part of Tung Chee Hwa's Principal Officials Accountability System.
The scheme, although heavily debated, allowed the public to have visibility to major transportation companies' fare policies in relations to micro and macro economic trends and indicators.