In principles of language learning and teaching,Brown talks about 12 principles of second language learning on which our teaching can be based.The authors chose two principles to further discuss and would give some practical suggestions.The principle of strategic investment is related to cognitive theory.Brown equates the learner’s“methods”―a position of equal importance with teacher’s methods.In other words,it emphasizes that a learner successfully masters the second language due to a large extent to his/her own personal“investment”of strategies.Thus,English teachers need to guide the learners to use different learning strategies.Another principle is the self-confidence.Self-confidence belongs to affective principles.Self-confidence has been directly connected the situation that a person believes in his/her own ability to accomplish the task.Self-confidence is the first step in learning English well because a confident student often play an active role in class and think quickly.This paper mainly discusses the functions of the self-confidence and strategies investment principles in students’learning and English teaching in second language.This study aims to encourage English teachers to employ the two principles during teaching process and enable students to enjoy the English learning.In the end,the authors also give some pedagogical implications to second language teaching.