Learning a second language is very difficult, especially, for the disabled; the disability may be a barrier to learn and to utilize information written in text form. We present the SignMT, Thai sign to Thai machine translation system, which is able to translate from Thai sign language into Thai text. In the translation process, SignMT takes into account the differences between Thai and Thai sign language in terms of both syntax and semantic to ensure the accuracy of translation. SignMT was designed to be not only an automatic interpreter but also a language learning tool. It provides meaning of each word in both text and image forms which is easy to understand by the deaf. The grammar information and the order of the sentence are presented in order to help the deaf in learning Thai, their second language. With SignMT, deaf students are less dependent on a teacher, have more freedom to experiment with their own language, and improve their knowledge and learning skill. In our experiment, SignMT was implemented to translate sentences/phrases which were collected from different sources including textbooks, cartoons, bedtime story, and newspapers. SignMT was tested and evaluated in terms of the translation accuracy and user satisfaction. The evaluation results show that the translation accuracy is acceptable, and it satisfies the users' needs. (Contains 8 tables and 9 figures.)