Koo began to study painting under Chao Shao An in 1963, Hu Nien Tsu in 1969 and continued with the master of contemporary Chinese ink painting, Lui Shou Kwan in 1974. She has since established her own unique style, painting mostly landscapes shrouded in clouds and mist. Her landscapes are conceptual, realized through interweaving lines that inspire impressions of miniscule cracks on ancient stone tablets, and through layers of ink wash, achieve an ethereal atmosphere of otherworldly beauty.

She has exhibited twenty-eight times as a solo artist since 1971 in places as varied as Taiwan, Hong Kong, Singapore, Malaysia, Thailand, the United States and Canada. She was awarded the Urban Council Artist Award by Hong Kong Museum of Art in 1977.

She has taught Chinese ink painting courses at the Department of Extramural Studies at The Chinese University, Hong Kong, and also at Chinese ink painting workshops in both the State University of Utah and Utah University, Salt Lake City.

Since 1986, both Sotheby’s and Christie’s in Hong Kong have auctioned her works annually.

Her works have been collected by organizations such as the State University of Utah, The University of Hong Kong, Hong Kong Museum of Art, Hong Kong Stadium, the Canadian Consulate General, Bank of America, Citibank, Bank of Australia, Hutchison Global Crossing Limited and Shaw Brothers (Hong Kong) Limited in Hong Kong respectively.