The article discusses the principles of three languages proficiency, studying second foreign language, specifically German after English and native language. This problem became actual after implementation of FSES at general school, where studying second foreign language is compulsory. Along with cognitive and communicative principles authors analyze the principle of positive transfer of similar language and culture aspects as well as teaching plans, principle of collaborative with students analysis of the interference phenomenon of two foreign languages being studied, principle of intensive semantic orientation of teaching, principles of intensification of education and saving study time. The authors stress that the basis of studying second foreign language must be a text and not a separate language phenomenon and pro-active attitude of students. 

Keywords: compulsory second foreign language, principles of teaching the second foreign language, cognitive and communicative principle, interference phenomenon and transfer of similar language and culture aspects as well as teaching plans, intensification of education, semantic orientation of teaching, text as a basis of studying, pro-active attitude of students.