There are several languages In Indonesia so that can be called a country of bilingualism. This study aims to analyze what are code-mixing types in the English learning process in Junior High School for the seventh-grade students of Ky Ageng Giri in the academic year 2018/2019, and explain how does the teacher mix language in the English learning process in Junior High School for seven grade students of Ky Ageng Giri in the academic year 2018/2019. Therefore code mixing is a solution in that phenomenon. This research was carried out in seventh grade Junior High School of Ky Ageng Giri, located in Girikesumo, Banyumeneng, Mranggen, Demak. Researcher used descriptive analysis methods, where researchers analyzed the type of code mixing using Muysken theory. Based on the data that has been obtained through the observation in the data, code mixing actually takes place in a conversation between the teacher and students in the language learning process. After collecting data, the researcher was found 26 (twenty-six) data contained in the observation, 7 (seventeen) including insertion, 3 (three) alternations, and 6 (six) congruent lexical. Then the reasons for using code mixing are also found in the data including attitudinal type and linguistic type