關係子句通常都能簡化為更精簡的單位。因此，在英文寫作中，可以考慮刪除一些不必要的字，讓關係子句縮短，把句子變得更簡潔。以下將介紹簡化關係子句的幾種方法：
方法一：將關係子句改為形容詞片語
Jane, who was late again today, sat next to me during lunch.
簡化後：Jane, late again today, sat next to me during lunch.
The wife, who was angry with her husband, did not return home last night.
簡化後：The wife, angry with her husband, did not return home last night.
以上兩個例句中，關係子句內的關係代名詞 + “be” 動詞（who was）一起省略掉後就能簡化成形容詞片語。省略後的形容詞片語功能上與原句的關係子句一樣修飾前面的名詞。
方法二：將關係子句改為分詞片語
The dog which is sitting at the door is waiting for its owner.
簡化後：The dog sitting at the door is waiting for its owner.
同樣地，原句中的關係代名詞 + “be” 動詞（which is）可以省略，把關係子句簡化成分詞片語。
而以下兩個例句則使用另一種簡化方式。
The man who lives next door teaches in a public school.
簡化後：The man living next door teaches in a public school.
句中的 “who” 與 “lives” 是主動關係，把關係代名詞 “who” 拿掉之後，動詞 “lives” 改為表示主動的現在分詞 “living”，“living next door” 則為簡化過後的分詞片語，修飾前面的名詞 “the man”。
Students who hand in the report late will lose five marks.
簡化後：Students handing in the report late will lose five marks.
句中的 “who” 與 “hand in” 這個動作是主動關係，把關係代名詞 “who”刪除後，動詞 “hand” 改為現在分詞 “handing”，簡化成分詞片語，修飾名詞 “students”。
We all read the e-mail that was sent by the manager earlier today.
簡化後：We all read the e-mail sent by the manager earlier today.
Discrimination that is based on race, gender, age, or disability is not allowed.
簡化後：Discrimination based on race, gender, age, or disability is not allowed.
以上兩個例句中的關係字句使用被動語態，直接將關係代名詞 + “be” 動詞（that was / that is）省略後就形成過去分詞的分詞片語。
方法三：將關係子句改為介系詞片語
The woman who is in the meeting room is our new team member.
簡化後：The woman in the meeting room is our new team member.
此句同樣出現關係代名詞 + “be” 動詞（who is），省略後剩下 “in the meeting room” 的部分就是介系詞片語。
The two-story house that had a beautiful front yard was sold $300,000.
簡化後：The two-story house with a beautiful front yard was sold $300,000.
關係子句中即使沒有關係代名詞 + “be” 動詞的部分還是能夠簡化為介系詞片語。以上句為例，原來關係子句中的動詞 “had” 可以使用介系詞 “with” 替換，將關係代名詞刪除後就能形成介系詞片語。
另外，一個關係子句不一定只有一種簡化方式，以下兩個例句除了能用分詞片語寫也能用介系詞片語寫。
The student who is wearing a blue jacket is a member of the science club.
簡化後：The student wearing a blue jacket is a member of the science club.The student in a blue jacket is a member of the science club.
The lady who is standing on the stage is the newly elected mayor.
簡化後：The lady standing on the stage is the newly elected mayor.The lady on the stage in the newly elected mayor.
