The research entitle The Language Diversity of Ethnic Chinese Traders in Interaction of Buying and Selling at Margasari Market Tegal Regency ( a Study of Sociolinguistic) this research aims to describe: (1) A language pattern of Chinese ethnic traders in interaction of buying and selling; (2) A utterance form of Chinese ethnic traders in interaction of buying and selling; (3) A utterance Level of Chinese ethnic traders in interaction of buying and selling; (4) Factors that determine the choice of language of ethnic Chinese traders in interaction of buying and selling. The method applied in this research includes the type of research, research sites, data and source of data, and research method. Type of this research was used descriptive qualitative approach. The research was conducted in the Margasari market, Tegal regency. Research data includes two kinds of which is premier and secondary data. Premier data in the form of utterance form of ethnic Chinese traders in interaction of buying and selling. Secondary data in the form of information about the background of social and cultural, and situational as the result of observation and interview. A source of the data in this research was ethnic Chinese traders with the buyer. The method in this research was used the determining element classification technique. Continued by a method of provision of data, the data analysis and display analysis. Conducted a method of a look at provision of data, a method of record and methods list. The Analysis steps, data analyzed through two procedures that was during the process of the analysis of data collection and analysis after a process of data collection. The display stage of the data analysis result was used formal method. The results of the analysis show that: (1) A language pattern of ethnic Chinese traders in interaction of buying and selling; (2) A utterance form of ethnic Chinese traders in interaction of buying and selling; (3) A utterance Level of ethnic Chinese traders in interaction of buying and selling; (4) Factors that determine the choice of language of ethnic Chinese traders in interaction of buying and selling. A language pattern there are two a pattern that is a language pattern of immature Chinese ethnic traders and language pattern of mature Chinese ethnic traders. A utterance form of Chinese ethnic traders in interaction of buying and selling: (1) the seller and buyer dominant was used Java language; (2) the seller and buyer dominant was used Indonesian language; (3) the seller dominant was used Java language, the buyer dominant was used Indonesian language; (4) the seller dominant was used Indonesian language, the buyer dominant was used Java language; (5) the seller and buyer dominant was used Chinese language; and (6) the seller dominant was used Chinese language, the buyer dominant was used Indonesian language. A utterance Level of Chinese ethnic traders: (1) a form of single variation language, includes Indonesian and Java Language; (2) a form of code-switching, includes code-switching from Indonesian language to Java language and code switching from Java Language to Indonesian language; and (3) a form of code-mixing. Factors that determine the choice of language of ethnic Chinese traders in interaction of buying and selling that was utterance situation, utterance participants and the choice of language own.