System.Drawing.Printing.PrinterSettings ps = new System.Drawing.Printing.PrinterSettings();
ps.DefaultPageSettings.Color = false;
ps.DefaultPageSettings.PrinterSettings.DefaultPageSettings.Color = false;
Aspose.Pdf.Facades.PdfViewer viewer = new Aspose.Pdf.Facades.PdfViewer();
viewer.PrintPageDialog = false;
viewer.AutoResize = true;
viewer.AutoRotate = true;
viewer.BindPdf(fromPath);
viewer.PrintDocumentWithSettings(ps);
viewer.Close();
依然为彩色打印。