This study aims to obtain a description of the characteristics of the language and variety of languages used in posts on Buying and Selling Used Goods Sukoharjo on Facebook social media, as well as the relationship between the use of language in Sukoharjo Used Goods Buying and Selling posts on Facebook social media and learning Negotiation Texts. This research belongs to the type of qualitative research. The research design is descriptive qualitative research. Data was obtained from posts by members of Sukoharjo Used Goods Buying and Selling Group. The data collection technique used is documentation. The analytical method used in this study is critical discourse analysis. The survey results are as follows (1) Language characteristics in the post Group Buying and Selling Used Goods Sukoharjo found 16 characteristics of non-standard language, which means that in the process of communication on social media, often use nonformal language that is not by Indonesian rules. (2) The variety of languages in the Sukoharjo Used Goods Buying and Selling Group are Slang, jargon, terms, and mixed codes. The variety of jargon language is the type that is most often found because, in this Group, the majority discusses buying and selling, so many words are used that are limited to buying and selling only. (3) The use of language, both language characteristics and variety of languages in the posts contained in the Sukoharjo Used Goods Buying and Selling Group, can be related to the learning of negotiating texts in high school class X in KD 3.11 and KD 4.11.