(SqlConnection connection = new SqlConnection(conn))

{

connection.Open();

DataSet ds = new DataSet();

SqlDataAdapter adp = new SqlDataAdapter("select col1,col2,col3,col4 from yourtable",connection);
adp.Fill(ds, "yourtable");

this.radMultiColumnComboBox1.DataSource = ds.Tables[0];

FilterDescriptor descriptor =

new FilterDescriptor(this.radMultiColumnComboBox1.DisplayMember, FilterOperator.StartsWith, string.Empty);

this.radMultiColumnComboBox1.EditorControl.FilterDescriptors.Add(descriptor);

this.radMultiColumnComboBox1.DropDownStyle = RadDropDownStyle.DropDown;

this.radMultiColumnComboBox1.EditorControl.Columns[0].HeaderText = "mycolumns1";//change your col1

this.radMultiColumnComboBox1.EditorControl.Columns[1].HeaderText = "mycolumns2";//change your col2

this.radMultiColumnComboBox1.EditorControl.Columns[2].HeaderText = "mycolumns3";//change your col3

this.radMultiColumnComboBox1.EditorControl.Columns[3].HeaderText = "mycolumns4";//change your col4

void yourform_Load(object sender, EventArgs e)

{

this.radMultiColumnComboBox1.AutoSizeDropDownToBestFit = true;

RadMultiColumnComboBoxElement multiColumnComboElement =

this.radMultiColumnComboBox1.MultiColumnComboBoxElement;

multiColumnComboElement.DropDownSizingMode = SizingMode.UpDownAndRightBottom;

multiColumnComboElement.DropDownMinSize =

new Size(420, 300);

multiColumnComboElement.EditorControl.MasterGridViewTemplate.AutoGenerateColumns =

false;

this.radMultiColumnComboBox1.AutoFilter = true;

changeyourcolumnsname();

}