Rapid economic growth in China leads to severe environment problems, and environmental protection and governance require firms to implement environmental responsibilities, especially to launch eco-innovation. It argues that product market competition and management moral cognition are the important factors affecting firm eco-innovation. Market competition with different features plays the obviously differentiated role in eco-innovation, and there is an inverse U-shape quadratic curve relationship between market competition and firm eco-innovation. Management moral cognition can promote firm eco-innovation, but this positive promotion role is conditionally dependent on external market competition contexts. When the firms have the monopoly power and insufficient eco-innovation willingness, management moral cognition can drive firms to increase eco-innovation expenditures. But when firms face (or are close to) complete competition market, fierce competition results in the inadequate role of management moral cognition in promoting eco-innovation due to the lack of internal resources of firms. The conclusions provide decision-making reference for governments, help to guide firms to carry out eco-innovation practice, and paly the active role in promoting firm clean production and protecting ecological environment.