【Abstract】As a component of language proficiency， lexical ability is essential to language learners， and a flurry of scholarly work in the last several decades has confirmed its importance to the academic world as well as language teaching （e.g. Coady & Huckin 1997， Nation 1990， 2001， Schimit & McCarthy 1997， Singleton 1999 etc.）. This paper aims to illustrate that it is feasible to use semantic-association method to boost the study of active words by raising language learners’ consciousness and activating the associative networks of vocabulary in learners’ mental lexicon. Based on the rationale that vocabulary of a language is an organized network of sense-relations， this paper designs a series of classroom activities aiming at activating peoples’ mental lexicon and producing more varied and advanced vocabulary in their writing. In this paper， chapter one introduces the definition and description of passive words and active words. Following chapter one， chapter two focuses the theory and its application in teaching. And in the last chapter， several classroom activities are designed to improve the active use of vocabulary.
　　【Key words】passive words； active words； semantic-association
　　1. Passive words and Active Words
　　Almost everyone has met words that can be understood perfectly well in a text， but fail to be remembered when used productively. This phenomenon may largely result from the distinction of active/passive words or receptive/productive words （hereafter R & P）. Although there remains a lack of clarity over definition of the notions of R & P， many scholars manage to explain R&P from various aspects.
　　Nation （2001： 24） describes R&P as pedagogic conceptions：
　　Receptive carries the idea that we receive language input from others through listening and reading and try to comprehend it， productive that we produce language forms by speaking and writing to convey messages to others.
　　In his opinion， passive vocabulary use involves the cognitive process of perceiving a word form and retrieving its meaning； while active word use involves that of wanting to express a meaning orally or in the written form and of retrieving and producing the appropriate spoken or written word form.
　　Melka （1997： 85） describes R&P based on the rationale that lexical knowledge is a continuum consisting of several levels of knowledge：
　　Certain degrees of knowledge could be labeled as ‘higher’ degrees of familiarity， close to productive knowledge， but at which point receptive knowledge can be converted into productive knowledge is clearly not easy to answer.