[Purpose] This study is a single-subject longitudinal study observing changes in sign language, spoken language, and syntax development and use of sign language, spoken language, sign language + spoken language used at home and daycare centers in children with hearing impairments in a bilingual environment with deaf parents. . Since there is a possibility of using or using sign language and spoken vocabulary in children with hearing impairments in a bilingual environment and in subsequent communication situations, this study aims to help with the importance of and early language development education for children with hearing impairments in the educational field. [Method] For children with hearing impairments in a bilingual environment, the development of sign language and spoken vocabulary and part-of-speech development at homes and day care centers where communication situations were held from September 03, 2018 to January 10, 2020 were confirmed by standardized tests. The average length and change of use by means were taken with observation cameras for 7 sessions before and after 2 months and analyzed by analysis of spontaneous speech and observation record table. [Results] First, the vocabulary development of sign language and spoken language reached the level of children of the same age. It was 81.4% with 57 points for nouns, 95.0% with 19 points for verbs, and 40.0% with 4 adjectives. Second, the average length of phrases was from sign language, session 1. 14 to 7.96, and spoken language 1 session 0.92 (-2SD) to 7 session 3.02. Third, the change in usage rate in bilingual environment families was in the order of sign language 77%, sign language + spoken language 23%, and spoken language 0%. In daycare centers, spoken language 95%, spoken + spoken language 5%, and signed language 0%. [Conclusion] Hearing-impaired children used sign language and spoken language effectively in the vocabulary development of sign language and spoken language, syntax development, and bilingual environment. Therefore, it is considered that the strategy of approaching language guidance for children with hearing impairments in a bilingual environment with various comprehensive language guidance methods that can promote the development of sign language and spoken language in their first language is essential.