Numeral classifiers are obligatory while expressing quantity in languages such as Mandarin Chinese. Their function is both grammatical and semantic. Different linguists in their studies state that classifiers are also closely related to categorization (Allan 1977, Goddard 2011, Tai 1994 etc.). In Mandarin Chinese, ke and zhu represent classifiers for semantic category of plants and trees. However, the distinction between their senses, semantic functions, nouns and numerals they are used with is not really clear. This thesis examines usage of classifiers ke and zhu in Mandarin Chinese. The paper is divided into theoretical and analytical part. Theoretical part introduces numeral classifiers topic among different languages, difference between measure words and numeral classifiers, their general categorization and a separate chapter focuses on numeral classifier system in Mandarin Chinese. Analytical part is based on corpus analysis. By analyzing tokens given by linguistic corpus Sketch Engine, this thesis examines nouns used with classifiers ke and zhu. Analysis' issue is to find out what can corpus-based analysis say about classifiers' semantic functions. Except of nouns analysis, this thesis also analyze most used numerals and argues whether classifiers categorize numerals they are used with too.