控件属性和InitializeComponent()关系：

 namespace Test22
 {
     partial class Form1
     {
         /// <summary>
         /// 必需的设计器变量。
         /// </summary>
         private System.ComponentModel.IContainer components = null;

         /// <summary>
         /// 清理所有正在使用的资源。
         /// </summary>
         /// <param name="disposing">如果应释放托管资源，为 true；否则为 false。</param>
         protected override void Dispose(bool disposing)
         {
             if (disposing && (components != null))
             {
                 components.Dispose();
             }
             base.Dispose(disposing);
         }

         #region Windows 窗体设计器生成的代码

         /// <summary>
         /// 设计器支持所需的方法 - 不要
         /// 使用代码编辑器修改此方法的内容。
         /// </summary>
         private void InitializeComponent()
         {
             this.numericUpDown1 = new System.Windows.Forms.NumericUpDown();
             ((System.ComponentModel.ISupportInitialize)(this.numericUpDown1)).BeginInit();
             this.SuspendLayout();
             //
             // numericUpDown1
             //
             this.numericUpDown1.DecimalPlaces = ;//属性里对应！！！！！
             this.numericUpDown1.Location = new System.Drawing.Point(, );
             this.numericUpDown1.Name = "numericUpDown1";
             this.numericUpDown1.Size = new System.Drawing.Size(, );
             this.numericUpDown1.TabIndex = ;
             //
             // Form1
             //
             this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);
             this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
             this.ClientSize = new System.Drawing.Size(, );
             this.Controls.Add(this.numericUpDown1);
             this.Name = "Form1";
             this.Text = "Form1";
             this.Load += new System.EventHandler(this.Form1_Load);
             ((System.ComponentModel.ISupportInitialize)(this.numericUpDown1)).EndInit();
             this.ResumeLayout(false);

         }

         #endregion

         private System.Windows.Forms.NumericUpDown numericUpDown1;
     }
 }

控件中小数点位数和InitializeComponent()里面的代码相呼应，而下面的代码又设置了2，所以覆盖掉了，代码和运行结果如下：

 using System;
 using System.Data;
 using System.Drawing;
 using System.Text;
 using System.Windows.Forms;
 namespace Test22
 {
     public partial class Form1 : Form
     {
         public Form1()
         {
             InitializeComponent();
         }
         private void Form1_Load(object sender, EventArgs e)
         {
             numericUpDown1.Maximum = ;
             numericUpDown1.Minimum = ;
             numericUpDown1.DecimalPlaces = ;
         }
     }
 }