This study examines collocates of two near-synonyms safety and security, drawing data from two general corpora (BNC Written and COCA Written) and one self-built specialized corpus (IMO Corpus). Collocates are extracted by Wordsmith 6.0; then a network analysis is given on some interesting collocates. Firstly, diachronic analysis exhibits a stable usage of safety whereas two big leaps of security in 1920-1930 and in 2000. In addition, it has been discovered that some generalizations made by industrial and information fields cannot be applied to the maritime-related words in a specialized corpus. Specifically, non-maritime-related general collocates tend to show very clear preference on safety and security in IMO corpus whereas maritime-related words have various behaviors when collocating with safety and security. Thirdly, network analysis by Netminer 4.0 is given on some shared interesting collocates such as maritime and ship, providing the brokerage role analysis for the differences between safety and security. At last, a semantic domain network analysis is displayed to explain how near-synonyms are different and similar based on their common and exclusive semantic domains.