import product change order of variants

when I import a product from csv,
it changes the order of variants

What CSV are you using ?

I tried to modify csv with Microsoft Excel and also with Open Office.

After that I made this test:

I export a product and import without open it,
also in this case the order of variants is changed.

The order of variants in the characteristics on the product page is defined by the ordering of the values of the characteristic. It is not related to the variant data so you can't change that via CSV. So I'm still not sure on what you're talking about I'm afraid.