How you fox this problem if you have mom that do not like your girlfriend that you love so much??
Well, that depends on why your mom doesn't like your girlfriend and your age but in the vast majority of cases it's best to accept you likely won't change her mind.
The first step at any age is to ask your mom to respect that you've made a choice to love and be with your current girlfriend. Ask her to cease any commentary that is negative towards your girlfriend and other similar talk like maybe how she wishes you'd break up or you would like another girl or whatever. In some cases that works, but in others it may not.
If asking for your choice to be respected fails the best thing you can do from there is avoid her. As an adult don't visit or call more often than necessary, and make it known you are ceasing contact because she refuses to give you the respect of an equal adult. Chances are if she isn't going to respect your choice in girlfriend and to keep her negative commentary to herself she's not respecting you in other areas of your life as well and as much as it might hurt ceasing contact is likely better for you and your mental health anyway even if you don't realize it at first.
If you're a minor in this situation, however, and asking her to respect your choice fails there really isn't much to do. Chances are she isn't going to see reason and attempting that will simply be a circular argument you will not win. Your best shot there is to hang out with your girlfriend outside your house (like in public spaces or at her house or some such) and avoid talking about her around your mother.
It sucks when people who are supposed to support us look at the people we love and dislike them, but the chances are high you aren't going to change their minds about it. The best thing you can do is make it known you don't appreciate their attitude and then avoid the subject to not spark further need for comment.