What do you mean by "it have being translate to other language"? If your TsiLang component has more than one language, then it holds as original captions (Languge #1) as well as translated to other languages ones. You will need just set TsiLang.ActiveLanguage = 1 in design-time and all captions on the form will get their original values.
what i menas is, after tsilang translate the form, i wan to retrieve the original text of my tbutton without set the language back to original language in run time.
You can use in run-time the TsiLang's public method
function GetStringValue(AStrings: pStrings; AName: Tstring; ALang: Integer): Tstring;
where AStrings - pointer to a string list; AName - name of a component or string identifier; ALang - number of language (use 1 for default language).
For example, to extract default caption for Button1 you can use:
...
var
S: string;
...
S := siLang1.GetStringValue(@siLang1.Captions, Button1.Name, 1);
...
or more compactly:
...
with siLang1 do
S := GetStringValue(@Captions, Button1.Name, 1);
...