Program:

static class Program
{

/// <summary>
/// 應用程序的主入口點。
/// </summary>
[STAThread]
static void Main(string[] args)
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
if (args.Length == 0)
Application.Run(new Form1());
else
Application.Run(new Form1(args));
}
}

Form1:

string[] args = null;
public Form1()
{
InitializeComponent();
}
public Form1(string[] args)
{
InitializeComponent();
this.args = args;
}

啟動方式：

Process.Start("a.exe", richTextBox1.Text);

C# Winform程序之間如何傳遞和接收參數 Process