public class Student

        {

            public int Id { get; set; }

            public string FirstName { get; set; }

            public string LastName { get; set; }

        }

        private DataTable ConvertDataToDataTable<T>(IEnumerable<T> list)

        {

            var type = typeof(T);

            var properties = type.GetProperties();

            var dataTable = new DataTable();

            dataTable.Columns.AddRange(properties.Select(x => new DataColumn(x.Name)).ToArray());

            foreach (var item in list)

            {

                var dataRow = dataTable.NewRow();

                foreach (var property in properties)

                {

                    dataRow[property.Name] = property.GetValue(item, null);

                }

                dataTable.Rows.Add(dataRow);

            }

            return dataTable;

        }

        [Test]

        public void XmlTest()

        {

            DataSet dataSet = new DataSet {DataSetName = "CustomDataSet"};

            Student student1 = new Student

            {

                Id = ,

                FirstName = "Chuck",

                LastName = "Lu"

            };

            Student student2 = new Student()

            {

                Id = ,

                FirstName = "Yong",

                LastName = "Zhang"

            };

            IEnumerable<Student> list = new List<Student>() { student1, student2 };

            var dataTable = ConvertDataToDataTable(list);

            dataTable.TableName = "Students";

            dataSet.Tables.Add(dataTable);

            string xml = dataSet.GetXml();

            Console.WriteLine(xml);

        }

<CustomDataSet>

  <Students>

    <Id>1</Id>

    <FirstName>Chuck</FirstName>

    <LastName>Lu</LastName>

  </Students>

  <Students>

    <Id>2</Id>

    <FirstName>Yong</FirstName>

    <LastName>Zhang</LastName>

  </Students>

</CustomDataSet>