The present study is based on a self-built Maritime English Law Corpus compared with BNC Baby as a reference corpus to explore some homogeneous features of four different maritime legal genres through the comparison of two different keyword analyses: corpus frequency-based keyword analysis and text dispersion-based keyword analysis. A comparison of keyword lists of four legal genres by using a cross-validation is also conducted to explore unique characteristics of each genre. The results show that two keyword methods generated both shared words and unshared words. According to the two criteria of keywords, we concluded that text dispersion-based keyword analysis is much better than traditional corpus frequency-based keyword analysis because the former meets both the content-distinctiveness of maritime-related keywords and the content-generalisability of law content keywords as well as showing more homogeneous maritime legal features than the latter.