尽管使用 TIniFile 类很方便, 但我觉得还是用系统 API 操作更顺手, 读写各只需要一行代码, 也不用 uses IniFiles.

本例效果图:



代码文件:
unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Memo1: TMemo;
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

const
  FilePath = 'C:\Temp\My.ini';

//写入 Ini 文件, 如果指定文件路径不存在会自动建立
procedure TForm1.Button1Click(Sender: TObject);
begin
  WritePrivateProfileString('段1', 'Key1', '值1', PChar(FilePath));
  WritePrivateProfileString('段1', 'Key2', '值2', PChar(FilePath));

  WritePrivateProfileString('段2', 'Key1', '值1', PChar(FilePath));
end;

//把写入结果显示在 Memo 看看
procedure TForm1.Button2Click(Sender: TObject);
begin
  if not FileExists(FilePath) then Exit;
  Memo1.Lines.LoadFromFile(FilePath);
end;

//读取测试
procedure TForm1.Button3Click(Sender: TObject);
var
  buf: array[Byte] of Char; {准备接受缓冲区}
begin
  GetPrivateProfileString('段1', 'Key2', '默认值', buf, Length(buf), PChar(FilePath));
  ShowMessage(buf);
end;

end.

窗体文件:
object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 148
  ClientWidth = 237
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  Position = poDesktopCenter
  PixelsPerInch = 96
  TextHeight = 13
  object Button1: TButton
    Left = 127
    Top = 24
    Width = 98
    Height = 25
    Caption = #20889#20837' Ini '#25991#20214
    TabOrder = 0
    OnClick = Button1Click
  end
  object Button2: TButton
    Left = 127
    Top = 65
    Width = 98
    Height = 25
    Caption = #30475#30475#20889#20837#32467#26524
    TabOrder = 1
    OnClick = Button2Click
  end
  object Button3: TButton
    Left = 127
    Top = 104
    Width = 98
    Height = 25
    Caption = #35835#21462'  Ini '#25991#20214
    TabOrder = 2
    OnClick = Button3Click
  end
  object Memo1: TMemo
    Left = 0
    Top = 0
    Width = 121
    Height = 148
    Align = alLeft
    Lines.Strings = (
      'Memo1')
    TabOrder = 3
    ExplicitHeight = 183
  end
end

相关函数还有:
WritePrivateProfileSection {}
WriteProfileSection        {}
WriteProfileString         {}
GetPrivateProfileInt       {}
GetPrivateProfileSection   {}
GetPrivateProfileStruct    {}
GetProfileInt              {}
GetProfileSection          {}
GetProfileString           {}

来源：https://www.cnblogs.com/del/archive/2008/06/02/1212120.html