The research aimed at 1) To investigate students' linguistic features of Englishes found in writing in the Facebook closed group's posts and comments, and 2) To investigate types of characteristics of localised features of Thai in English writing found in students' writing in the Facebook closed group's posts and comments. The participants were the second-year English major students who enrolled the course entitled "Teaching English Writing skill 1" at Bansomdejchaopraya Rajabhat University in 2018. The data were collected from the students' writing in the Facebook closed group's posts and comments and analysed with the qualitative method. The finding showed that the posts were mainly about life-learning. For linguistic features, syntactic features were mostly found in parts of speech, punctuation, verb tenses, and capitalisation, and lexical features were mostly found in word choices and spelling. In the aspects of localised features of Thai in English writing, the characteristics of translation and transfer were found the most, and the rest were code-switching, code-mixing, shift, and reduplication.