方法1: 

ArrayList list = new ArrayList();
    list.Add (new DictionaryEntry ("1","投诉"));
    list.Add (new DictionaryEntry ("2","举报"));
    list.Add (new DictionaryEntry ("3","建议"));
    list.Add (new DictionaryEntry ("4","表扬"));
    list.Add (new DictionaryEntry ("5","其它"));
    
    cbBoxLeiXing.DataSource =list;          
    cbBoxLeiXing.DisplayMember ="Value";
    cbBoxLeiXing.ValueMember ="Key";


 
方法2:  

DataTable dt=new DataTable();
    DataColumn col;
    DataRow row;
  
    col=new DataColumn();
    col.DataType=Type.GetType("System.Int16");
    col.ColumnName="value";
    dt.Columns.Add(col);
    
    col=new DataColumn();
    col.DataType=Type.GetType("System.String");
    col.ColumnName="text";
    dt.Columns.Add(col);
  
    //添加行
    row=dt.NewRow();
    row["value"]=1;
    row["text"]="投诉";    
    dt.Rows.Add(row);
  
    row=dt.NewRow();
    row["value"]=2;
    row["text"]="举报";    
    dt.Rows.Add(row);
  
    row=dt.NewRow();
    row["value"]=3;
    row["text"]="建议";    
    dt.Rows.Add(row);
  
    row=dt.NewRow();
    row["value"]=4;
    row["text"]="表扬";    
    dt.Rows.Add(row);
  
    row=dt.NewRow();
    row["value"]=5;
    row["text"]="其它";    
    dt.Rows.Add(row);
  
    this.cbBoxLeiXing.DataSource=dt.DefaultView;
    this.cbBoxLeiXing.DisplayMember="text";
    this.cbBoxLeiXing.ValueMember="value";


 
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方法3:
combox的item是object类型,具体显示的内容是通过ToString()方法得到的字符串。
所以你可以建一个“产品”类,并重写它的ToString()方法

class MyData
     {
       public string id;
       public string name;
  
       public override string ToString()
       {
         return name;
       }
     }
  
       // 插入数据
       MyData data = new MyData();
       data.id = "123";
        = "aaa";
       comboBox1.Items.Add(data);
        // 取得id
       MyData data = comboBox1.Items[index] as MyData;
       if(data!=null)
       {
         id = data.id;
       }