var list = (from province in db.Areas

        where province.ParentId ==  && province.IsDel ==

        join city in db.Areas on province.ID equals city.ParentId into citys

        from ci in citys.DefaultIfEmpty()

        join area in db.Areas on ci.ID equals area.ParentId into areas

        select new

        {

        ID = province.ID,

        Name = province.AreaName,

        FullName = province.FullName,

        Child = (from cy in citys

              where cy.IsDel ==

              select new

              {

                  ID = cy.ID,

                  Name = cy.AreaName,

                  FullName = cy.FullName,

                  Child = (from ar in areas

                       where ar.IsDel ==

                       select new

                       {

                       ID = ar.ID,

                       Name = ar.AreaName,

                       FullName = ar.FullName,

                       })

              })

        }).ToList();

return list;