那是因为你没有设置好打开方式

右键单击jsp文件jsp文件怎么打开方式，设置以下打开方式

Window>Preferences>General>File Associations

在右边的File types中选择*.jsp,下面的Associated editors中选择Myeclipse JSP Editor(default)(locked by ‘JSP’ content type)(locked by ‘JSF’ content type)(locked by ‘CSS’ content type)这一项，确认后退出即可