One of the key research issues of language attrition is lexical attrition. There have been a great number of empirical studies investigating the influencing factors of second language lexical attrition for more than 40 years. This article aims at clarifying the concept of language attrition and discuss the main influencing factors of lexical attrition, and suggesting potential directions for future research. After analyzing the relevant studies, we find the influencing factors of lexical attrition can be roughly divided into two categories, including objective factors such as attrition time, language acquisition methods, influencing factors related lexis, etc. and subjective factors of learners such as learners’ age, gender, emotional factors and so on. Combined with the factors that affect lexical attrition, this paper finally talks about the enlightenment on foreign language vocabulary teaching for China.