[Solved]-change order on my object list-LINQ,C#

The code looks fine. As Paul said you should not use save twice. I would also be tempted to remove some duplication with the following

    public void OrderUp(int favouriteId)
    {
        ChangeOrder(false, favouriteId);

    }

    public void OrderDown(int favouriteId)
    {
        ChangeOrder(true, favouriteId);
    }
    private void ChangeOrder(bool OrderDown, int favouriteId)
    {           
        UsFavourite currentFav = db.UsFavourites.FirstOrDefault(m => m.FavouriteID == favouriteId);

        // Get favourite by current favourite's order + 1
        UsFavourite tempFav;
        if (OrderDown)
        {
            tempFav = db.UsFavourites.OrderBy(m => m.FavouriteOrder).FirstOrDefault(m => m.FavouriteOrder > (currentFav.FavouriteOrder));
        }
        else
        {
            tempFav = db.UsFavourites.OrderByDescending(m => m.FavouriteOrder).FirstOrDefault(m => m.FavouriteOrder < (currentFav.FavouriteOrder));

        }
        if (tempFav != null)
        {
            //update tempFav
            tempFav.FavouriteOrder = currentFav.FavouriteOrder;

            //update currentFav
            currentFav.FavouriteOrder = currentFav.FavouriteOrder + change;
            Save();
        }
    }