richTextBox1.SelectionFont = new Font("Tahoma", 12, FontStyle.Bold);
richTextBox1.SelectionColor = System.Drawing.Color.Red;
这是MSDN上的代码!
C# code
private void Form1_Load(object sender, EventArgs e)
{
this.richTextBox1.Text = "abcdefghijk fff ffs fs";
richTextBox1.SelectionFont = new Font("f", 12, FontStyle.Bold);
richTextBox1.SelectionColor = System.Drawing.Color.Red;
}