Vocabulary learning is often seen as an important but also difficult aspect of learning English as a foreign language (EFL). Thus, it is particularly important to promote the sustainable development of vocabulary acquisition. Many features of English words affect the sustainable development of vocabulary acquisition, including frequency, polysemy, word family, part of speech, and word length. The influence of most of these factors on vocabulary acquisition has been extensively explored in previous studies, but the effects of cognateness and lexicalization remain unclear. This is in part due to the measurement tool, the Vocabulary Size Test, which does not include enough cognates and non-lexicalized words to adequately represent the language used in authentic contexts. To better our understanding of the effect of word features in the context of Chinese EFL learners, the present study modified the Vocabulary Size Test by including additional 19 non-lexicalized words and 33 cognates and administered it to 527 Chinese non-English major sophomores. The results revealed that cognateness, frequency, and polysemy were positively correlated with vocabulary acquisition, whereas word length and lexicalization were negatively correlated with acquisition. Further, multiple regression analysis indicated that cognateness, polysemy, and frequency were the largest contributors to acquisition.