Because I write many document with office word 2007 + mathtype.
I'm not request for libreoffice can edit mathtype's equations, but I want to know libreoffice can open all the office word 2007 documents or not?
libreoffice and openoffice are just clones separated due to policy reasons. But as far as word 07 is concerned, LO or OO may sometimes may not be so faithful in reproducing the exact same effect as in Word 07.
Some formatting mismatch you can always expect.
Yes, as others have stated, you can open Word 2007 documents with LibreOffice on Ubuntu. No one addressed MathType equations though, so let me mention that...
You already realize you can't edit MathType equations on Ubuntu, so as you stated, you don't expect to. The best experience when going from Word 2007 to LibreOffice on Ubuntu though, is for the Word document to be in .doc format -- not .docx. The main differences between the 2 when they're open in LibreOffice are fonts and alignment of the MathType equations.
When you save as .doc and open in LibreOffice, the fonts should be the same as what you used on Windows (assuming, of course, these fonts are present in Ubuntu). The equations should have roughly the same vertical alignment with surrounding text as they did in Word. With .docx, the fonts may be substituted, and the equations will be shifted up so the bottom of the equation is aligned with the baseline of the text.
There may also be an issue with the fonts used in the MathType equations. If some of the symbols don't show up, there are two things to check. First, check that the font MT Extra is installed in Ubuntu. If it is, make sure it's not a version that's dated earlier than 2001. If it's an old version, delete it and replace it with the one from your Windows installation of MathType. The second thing to check is whether you've installed the Ubuntu Restricted Extras, available from the Software Center. This includes additional Microsoft fonts.
Well, to make sure that you can use Libre Office without any problems you can easy test for it if it will work without any issues (and maybe start moving out from MS Office in to LibreOffice) using the portable version of LibreOffice.
No need for install, if it doesn't work just delete it and you are good.
You can get the portable version of LibreOffice here: http://www.libreoffice.org/download/portable/
Have a look and gl ;)