海綿寶寶大哥你好，我有嘗試過了，他的執行順序是:
[托管頁面的Page_Load->用戶控件的Page_Load->托管頁面的Page_PreRender->用戶控件的Page_PreRender]
所以這就是我對這句話的疑惑點，不過這本書是翻譯本，我在想會不會是翻譯錯了或是原文寫錯了?

我去找了原文
應該是翻譯錯了
應該不是「如果...就能夠...」而是「如果...就以為可以...你就會碰到未預期的...」

節錄原文如下

Thus, you would be able to set values in the Page_Load method of the hosting page and then access
those values in the control’s Page_Load method. However, if you ended up setting those values in
the hosting page’s Page_PreRender event handler (which comes after the Page_Load event handler),
yet expected to be able to access those values in the control’s Page_Load method, then you will get
unexpected behavior because those properties were not set as required. This can be mitigated by not
doing any work in your control until after Page_Load has been called.

海綿寶寶大神有心了，感謝解惑!