Too many unknowns to say Clerick. It could be the main is doing it's job, that your in an overload situation. What's the max amp rating on main? When it trips does it completely trip out, or does just part of the house go dead?
You may have to bring a qualified person to conduct load calculations, in order to determine if there is an overload of the main, or if you have an unbalanced panel. On the flip side of that coin, it could be as simple as a weak main.