简单。
procedure TForm1.Button1Click(Sender: TObject);
function isvaldate(s:string):boolean;
var y,m,d:word;
begin
try
y:=strtoint(copy(trim(s),1,4));
m:=strtoint(copy(trim(s),5,2));
d:=strtoint(copy(trim(s),7,2));
result:=isvaliddate(y,m,d);
except
result:=false;
end;
end;
begin
if isvaldate(edit1.Text) then
showmessage('ok');
end;