Word association (WA) is a psychologically and cognitively real mechanism for language acquisition and language processing with both qualitative and quantitative characteristics. The paper firstly introduces the three theoretical cornerstones of WA research; secondly reviews the existing empirical studies based on CiteSpace; thirdly investigates the WA protocols focusing on cue selection, response analysis, experimental control and subject idiosyncrasy; lastly discusses the research trends concerning context availability, lexical polysemy and two-word collocation.