protected void Button1_Click(object sender, EventArgs e)
    {
        string str=TextBox1.Text; 

        string pattern = @"(?is)^(-?0+|0+)(\.\d{1,6})$";
        Regex reg = new Regex(pattern);
        bool isValid = reg.IsMatch(str);
    }

------解决方案--------------------

Regex.IsMatch(s,@"^((-?1)|(-?0\.\d{1,6})|0)$")