The Affordance theory, proposed by cognitive psychologist Gibson from an ecological point of view, reveals the interaction between agent and the external environment, providing a new perspective for the study of second language acquisition. The environmental affordances are dynamic, pluralistic, hierarchical and differentiated. Therefore, in the second language acquisition, learners should effectively utilize diverse types of affordances in the environment, especially the happening affordance, give priority to the use of sure-fire affordances, material culture affordances and language affordances. The second language learners can perceive, use and shape those affordances of the environment through cross-module cognitive channels, and learn the language efficiently.