// Initialize PDF output stream
using (System.IO.Stream pdfStream = System.IO.File.Open("OXPStoDOCX.pdf", System.IO.FileMode.OpenOrCreate, System.IO.FileAccess.Write))
{

    // Initialize OXPS input stream
    System.IO.Stream oxpsStream = System.IO.File.Open("sample.oxps", System.IO.FileMode.Open);

    // Load input OXPS document
    XpsDocument document = new XpsDocument(oxpsStream, new XpsLoadOptions());

    // Initialize options object with necessary parameters
    PdfSaveOptions options = new PdfSaveOptions()
    {
        JpegQualityLevel = 100,
        ImageCompression = PdfImageCompression.Jpeg,
    };
    // Create rendering device for PDF format
    PdfDevice device = new PdfDevice(pdfStream);

    // Save output PDF file
    document.Save(device, options);
}

// Load the intermediate PDF file
Document pdfDocument = new Document("OXPStoDOCX.pdf");

// Save the output DOCX file
pdfDocument.Save("test.docx" , SaveFormat.DocX);