The study considers the competition and cooperation between mixed duopoly ports with service differentiation when both emission tax and partial privatization policies are implemented together. By developing three-game models between government and port enterprises, this paper first studies and compares, under different game scenarios, the optimal emission tax for mixed duopoly ports and privatization level for a semipublic port, as well as the optimal output (or pricing) and emission reduction of semipublic and private ports....