默认我们的DataGridView cell是没有边框的，无伦是正常状态还是编辑状态，因为系统把TextBox的BorderStyle值改成了None，所以这里首先要把BorderStyle值改回来，那至于是FixedSingle还是Fixed3D,就得看你自己需要了,我这里改成了FixedSingle,方便绘制

主要是继承　DataGridViewTextBoxCell　类，，需要在这里改点东西代码如下：

  public class DataGridViewTextBoxEditCell : DataGridViewTextBoxCell     {         public override void InitializeEditingControl(int rowIndex, object initialFormattedValue, System.Windows.Forms.DataGridViewCellStyle dataGridViewCellStyle)         {                         base.InitializeEditingControl(rowIndex, initialFormattedValue, dataGridViewCellStyle);             TextBox textBox = this.DataGridView.EditingControl as TextBox;             if (textBox != null)             {                 textBox.BorderStyle = BorderStyle.FixedSingle;//改回边框             }         }         protected override void Paint(Graphics graphics, Rectangle clipBounds, Rectangle cellBounds, int rowIndex, DataGridViewElementStates cellState, object value, object formattedValue, string errorText, DataGridViewCellStyle cellStyle, DataGridViewAdvancedBorderStyle advancedBorderStyle, DataGridViewPaintParts paintParts)         {             base.Paint(graphics, clipBounds, cellBounds, rowIndex, cellState, value, formattedValue, errorText, cellStyle, advancedBorderStyle, paintParts);                           //绘制边框             Rectangle cellBounds1 = new Rectangle(cellBounds.X + 2, cellBounds.Y + 1, cellBounds.Width - 4, cellBounds.Height - 3);             graphics.DrawRectangle(new Pen(SystemColors.WindowFrame), cellBounds1);         }      }           public class DataGridViewTextBoxEditColumn : DataGridViewColumn     {         public DataGridViewTextBoxEditColumn()             : base(new DataGridViewTextBoxEditCell())         {         }         public override DataGridViewCell CellTemplate         {             get             {                 return base.CellTemplate;             }             set             {                 // Ensure that the cell used for the template is a CalendarCell.                 if (value != null &&                     !value.GetType().IsAssignableFrom(typeof(DataGridViewTextBoxEditCell)))                 {                     throw new InvalidCastException("Must be a CalendarCell");                 }                 base.CellTemplate = value;             }         }     }          应用:     private void Form1_Load(object sender, EventArgs e)         {             DataTable dt = new DataTable();             dt.Columns.Add("name");             dt.Columns.Add("name1");             DataGridViewTextBoxEditColumn dataGridViewColumn = new DataGridViewTextBoxEditColumn();             dataGridViewColumn.HeaderText = "columns";             dataGridViewColumn.DataPropertyName = "name";             this.dataGridView1.Columns.Add(dataGridViewColumn);             DataGridViewTextBoxEditColumn dataGridViewColumn1 = new DataGridViewTextBoxEditColumn();             dataGridViewColumn1.HeaderText = "columns";             dataGridViewColumn1.DataPropertyName = "name1";             this.dataGridView1.Columns.Add(dataGridViewColumn1);             this.dataGridView1.AutoGenerateColumns = false;             this.dataGridView1.DataSource = dt;         }                  应该还有更多好的办法，希望大家能批评改正