unit Task;

interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls, ScktComp, ComCtrls,winsock, StrUtils, ExtCtrls, Spin, Menus,
Buttons,protocol,smpp;

type
TaskRecord= record
Time: TDateTime;
ConFile: String;
NumFile: String;
NextP: Pointer;
end;
TP=^TaskRecord;

implementation

end.
这是定义指针类型的unit

unit SCGroupSend;

interface

uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls, ScktComp, ComCtrls,winsock, StrUtils, ExtCtrls, Spin, Menus,
Buttons,protocol,smpp,Task,Unit2;

var
hed,p:TP;

为什么编译的时候说我的TP没有定义？

顺序换一下
TP=^TaskRecord;
TaskRecord= record
Time: TDateTime;
ConFile: String;
NumFile: String;
NextP: Pointer;
end;