如题

已经找到解决方法，一直没时间传上来和大家分享一下，

使用的是itextsharp

    /// <summary>
    /// 合并PDF文件
    /// </summary>
    /// <param name="lstFiles">要合并的文件列表</param>
    /// <returns></returns>
    private bool MergePDF(List<string> lstFiles)
    {
        bool bReturn = false;
        try
        {
            int f = 1;
            PdfReader reader = new PdfReader(lstFiles[f]);           
            int n = reader.NumberOfPages;
            Document document = new Document(reader.GetPageSizeWithRotation(1));           
            PdfWriter writer = PdfWriter.GetInstance(document, new FileStream(lstFiles[0], FileMode.Create));           
            document.Open();
            PdfContentByte cb = writer.DirectContent;
            PdfImportedPage page;
            int rotation;
            while (f < lstFiles.Count)
            {
                int i = 0;
                while (i < n)
                {
                    i++;
                    document.SetPageSize(reader.GetPageSizeWithRotation(i));
                    document.NewPage();
                    page = writer.GetImportedPage(reader, i);
                    rotation = reader.GetPageRotation(i);
                    if (rotation == 90 || rotation == 270)
                    {
                        cb.AddTemplate(page, 0, -1f, 1f, 0, 0, reader.GetPageSizeWithRotation(i).Height);
                    }
                    else
                    {
                        cb.AddTemplate(page, 1f, 0, 0, 1f, 0, 0);
                    }
                }
                f++;
                if (f < lstFiles.Count)
                {
                    reader = new PdfReader(lstFiles[f]);                   
                    n = reader.NumberOfPages;                   
                }
            }
            document.Close();
            bReturn = true;           
        }
        catch
        {
            bReturn = false;           
        }
        return bReturn;
    }
}