WMF is short for Windows Metafile.It contains a series of drawing operations, including commands for drawing lines, circles, and rectangles.It also contain bitmap drawing operations,used primarily for vector images, but can also include raster graphics.WMF files have largely been replaced by more standard formats, such as .jpg and .gif images. The WMF format is still supported by various programs, including Microsoft's Windows Photo Viewer, which is included in Windows 7.
If you want to convert mhtml to wmf format,HTML Converter Command Line can help you.
HTML Converter Command Line is a very powerful software which can allow you to convert web pages to PDF, PS (postscript), WMF, EMF vector formats,also allow you to create previews or thumbnails of web pages in a number of different formats, such as TIF, TIFF, JPG, JPEG, GIF, PNG, BMP, PCX, TGA, JP2 (JPEG2000), PNM, etc.
The command line application of HTML Converter is very convenient and easy to use,you can realize the conversion of mhtml to wmf only by some dos commands.You should only need the called program,source file.
HTML Converter Command Line can be downloaded at https://www.verypdf.com/htmltools/htmltools.zip. You can get more information about HTML Converter Command Line at https://www.verypdf.com/htmltools/index.html and https://www.verypdf.com/htmltools/htmltools-manual.htm.
The contents below are the details to the conversion of mhtml to wmf.
Step1.Please click 
button and click “run” in start menu.Then input “cmd” in “open” edit box and click “OK” button.Please see Figure1.
Figure1.
“Windows” + “R” can also open the dialog in Figure1.
Step2.In popup cmd.exe dialog box,you should input command lines.If the screen of the dialog box is disordered,you can use command “cls” to clear screen.Please see Figure2.
Figure2.
The conversion command lines are "C:\Documents and Settings\admin\Local Settings\Temp\htmltools\htmltools.exe" "C:\Documents and Settings\admin\Desktop\Google.mht" google.wmf
"C:\Documents and Settings\admin\Local Settings\Temp\htmltools\htmltools.exe" is the directory of htmltools.exe which is the called program in the conversion of mhtml to wmf.
"C:\Documents and Settings\admin\Desktop\Google.mht" is the directory of source file.
google.wmf is the name of target file.
When the sentences framed in red rectangle showed in Figure2 appear,it means the conversion is successful.
Step3.Find the target file in current directory.Please see Figure3.
Figure3.