In China, many students trying to learn new words, but the result is so disappointing. Why is the vocabulary so difficult to learn? The reason is that our New Senior English for China Student’s Book has raised greater demand for vocabulary: the senior school students are required to master 3,300-4,500 words and 400-500 phrases. Considering that millions of high school students in China are eager to achieve this goal and enlarge their vocabulary size, the teachers should help students to adopt effective ways to learn vocabularies more efficiently. But unfortunately, in China only a few researchers focus on vocabulary learning strategy and they just focus on one or two aspects in the research. And the learning of vocabulary has been underestimated in the field of second language acquisition for many years, so it is necessary to make researches on vocabulary learning strategies and has an important practical value.

II. vocabulary learning strategies

2.1 Definitions of vocabulary learning strategies
 vocabulary learning strategies refer to approaches, techniques, specific actions and behaviors that learners employ to facilitate their vocabulary learning both consciously and unconsciously. In this paper, vocabulary learning strategies refer to behavioral and mental activities that learners take to facilitate their vocabulary learning.
2.2 Researches on vocabulary learning strategies in Western Countries
 In recent years, the study on vocabulary learning has attracted a growing number of researchers, scholars, educationalists and teachers. And many linguists, both at home and abroad, have pointed out the importance of vocabulary learning strategies. Nation proposed different classification on vocabulary learning strategies, makes a distinction between initial discovery of word meanings. Oxford(1990) pided vocabulary learning strategies into social strategies, memory strategies. while Ellis and Benton(1993) survey students learning English using repetition and keyword strategy. They found that the key word strategy was really effective in translating foreign language into the native language，but significantly surpassed by repetition in translating native language into foreign language. Stoffer(1995) clustered her vocabulary strategy survey into nine groups: strategies involving authentic language use; strategies involving in creative activities; strategies used for self-motivation; strategies used to create mental connection; memory strategies;  visual strategies involving physical action; strategies used to overcome the anxiety and strategies used to organize words. Schmitt & McCarthy(1997) summarized these strategy classifications and proposed taxonomy of vocabulary learning strategies labeled discovery strategies and consolidation strategies．The former includes determination strategies and social strategies，and the later includes social strategies，memory strategies，cognitive strategies and meta-cognitive strategies． 高中生英语词汇学习策略的调查分析(2):http://www.youerw.com/yingyu/lunwen_39090.html