Mr Tse joined the former Environmental Protection Agency in 1985 which was subsequently reorganized in 1986 to become the current Environmental Protection Department (EPD). Throughout the service with EPD, Mr Tse had taken up a wide range of duties at professional and senior managerial levels. He was appointed as a Deputy Director of Environmental Protection in 2013 and subsequently as the Under Secretary for the Environment in August 2017.

He possesses a broad spectrum of experience in various areas of environmental protection, including law enforcement, computer modelling, environmental monitoring, environmental impact assessment and planning, policy development and cross-boundary cooperation with the Mainland.