I have finally find a solution for this problem, by this you can print all Turkish characters.
String htmlText = html.ToString();
Document document = new Document();
string filePath = HostingEnvironment.MapPath("~/Content/Pdf/");
PdfWriter.GetInstance(document, new FileStream(filePath + "\\pdf-"+Name+".pdf", FileMode.Create));
document.Open();
iTextSharp.text.html.simpleparser.HTMLWorker hw = new iTextSharp.text.html.simpleparser.HTMLWorker(document);
FontFactory.Register(Path.Combine(_webHelper.MapPath("~/App_Data/Pdf/arial.ttf")), "Garamond"); // just give a path of arial.ttf
StyleSheet css = new StyleSheet();
css.LoadTagStyle("body", "face", "Garamond");
css.LoadTagStyle("body", "encoding", "Identity-H");
css.LoadTagStyle("body", "size", "12pt");
hw.SetStyleSheet(css);
hw.Parse(new StringReader(htmlText));