As a boy, if you are thin, you can wear trousers. First of all, consider choosing some loose pants, which will not be too tight; Secondly, you can also consider choosing some pants specially tailored for thin people; In addition, you can also consider seeing if you have leggings that fit or casual pants of moderate length. In short: as a boy, if he is thin, he can wear pants. It is recommended to choose slacks that are loose, specially tailored or fit.