Prof. Mao Yushi attended and gave a brief speech entitled "Green Economy and Social Fairness" on the World Green Forum which was held on May 27th, 2011, in Hong Kong. He proposed the third dimension of evaluation besides economy and environment, that is, social fairness. Some projects are both beneficial to economy and environment, yet are harmful to social fairness. Therefore, it's hard to say such projects are good or bad.

Over thirty official representatives from the Europe, Canada, Australia, and other countries attended the forum. The World Green Forum has its fixed office in Hong Kong and mainly tackles green issues of the Europe and mainland China.