所谓复杂的定语从句，是指一个句子带有两个或两个以上定语从句的结构。这类定语从句在结构上与先行词的关系比较复杂，有如下几种形式：
1．自由式定语从句
自由式定语从句是指一个句子中两个或两个以上不同成分带定语从句的情况。这种从句的先行词没有固定模式，在句中充当不同的句子成分，故该结构中的定语从句称为自由式定语从句。它们拆开来看，其实就是一个一个简单的定语从句，因此，其翻译也和简单的定语从句相同。如：
Thus the Arab Umayyed dynasty of caliphs, which had moved the capital
from Medine to Damascus in 661, came to be regarded with much justification
as a parasitic clique that had outlived its usefulness once the conquests
were completed.
人们开始理由充分地认为，阿拉伯伍麦叶里发王朝是征服战争完成后毫无作用的一个寄生集团；伍麦叶王朝曾于661年从麦地那迁都大马士革。
该句中由which和that 引出两个定语从句，分别修饰做主语用的the Arab Umayyed dynasty of caliphs
和作宾语用的 a parasitic clique，翻译时一个被译成并列句，一个被译成定语。
2．嵌套式定语从句
嵌套式定语从句是指一个句子中定语从句套定语从句的情况。这种结构中的定语从句其实和自由式定语从句基本相似，拆开来也是一个独立的定语从句，只不过一个定语从句在另一个定语从句之中而已。因此，其翻译也与简单的定语从句相同。这里也仅举一例加以说明：
Likewise in the east were the Seljuk Turks who had infiltrated from their
Central asinan homeland into the Islamic Empire where they were employed
as mercenaries by the Baghdad caliphs.
同样，在东方是塞尔柱突厥人，他们从家乡中亚进入伊斯兰教帝国；在那里被巴格达哈里发雇为雇佣军。
该句中有两个定语从句，即在由who引出的定语从句中又套了一个由where引出的定语从句。翻译时，可按翻译简单的定语从句的方法。这里，两者均被译成了并列句，分别修饰先行词the
Seljuk Turks 和 the Islamic Empire。
3．并列式定语从句
并列式定语从句是并列成分中的定语从句的简称，指一个句子中两个或两个以上并列成分均带定语从句的情况。笔者刊登在《中国翻译》（96.1）上的《英语并列成分中定语从句的汉译》一文曾作过介绍。这里再补充一点，这类定语从句也可译成状语从句，即先把主句译出，再把定语从句译成两个表示并列或转折关系的状语从句。
This was a defensive pact, designed to protect Germany against the French,
who aspired to recover the alsace-Lorraine provinces lost in 1871, and
also to protect Austria-hungary against the Russians, with whom they continually
clashed in the Balkans.
这是一个防御性的盟约，旨在保护德国人免受法国人的攻击，保护奥匈帝国免受俄国人的攻击；因为法国人想收复1871年失去的阿尔萨斯-洛林地区，而俄国人则在巴尔干半岛同奥匈帝国接连不断地发生冲突。
4．一主二仆式定语从句
一主二仆式定语从句是指一个先行词带有两个或两个以上定语从句的情况。该结构中的定语从句比较规范，均修饰一个先行词，在翻译时，虽然也遵循一般定语从句的翻译技巧和方法，但还有其独特的地方。归纳起来，有如下几种情况：
1）译成定语 可以把两个定语从句译成并列的定语，也可译成分开的定语修饰先地词，或分别修饰重复的先行词。
… and the old ways of earning a living rivalled by new agricultural techniques,
by commerce with hitherto unknown parts of the globe, and by new crafts
with strane machines that saved labor and that ran without the traditional
human or animal power
……古老的谋生之道正受到新的农业技术、新的贸易、新的行业的挑战；这种新贸易是与世界上一向无人知晓的地区进行的贸易，而种种新行业则是使用一些无需传统的人力畜力驱动、可节省劳动力的奇特机遇。（并列的定语）
Almost everything which really matters and which the world possessed
at the commencement of the modern age was already known to man at the dawn
of history.
近代史开始时，世界拥有的每一项重大成就，已为历史发端期的人们所知晓。（分开的定语）
And it helps to explain why so many inventions that were of Chinese origin
or that had been known to the Greco-Romans, were fully developed and exploited
ony by the Western Europeans.
它有助于说明，为什么发源于中国的许多发明和希腊罗马人所知道的许多发明，只是在西欧人手中才得到全面发展和充分利用。（分开的定语修饰重复的先行词）
2）译成并列句 可以把两个定语从句简单地译成一个并列句，也可以把它们译成两个分开的并列句，用来表示并列、转折或先后顺序等关系：
Consequently the manor was a self-sufficient vilage that was worked by
serfs who were not free to leave, and who with their labor supported a
hierarchy of lay and clerical lords.
因而，采邑是靠农奴经营的自足自给予的村庄；农奴不能随便离开，并以其劳动养活教俗封建集团。（一个并列句）
Not Surprisingly, the most complex political structures appeared in the
Sudan, where long distance trade was most highly developed and where Islamic
influence was the strongest.
毫不奇怪，苏丹出现了最复杂的政治组织，在那里，长途贸易发展得最快，伊斯兰教的影响最为强烈。（两个并列句）
Our aim is to establish in Ghana a strong and progressive society … where
poverty and illiteracy no longer exist and disease is brought under control;
and where our educational facilities provide all the children of Ghana
with the best possible opportunities for the development of their potentialities.
我们的目的是在加纳建立一个强大、进步的社会……在这里，贫困和文盲不再存在，疾病得到控制；在这里，我们的教育机构为加纳所有的孩子提供发展他们的潜力的最好机会。（两个并列句，表示并列关系）
This hope was nurtured by the great victories won by Genghis Khan''s grandson,
Hulagu, who was a Buddhist, and whose wife was a Christian.
成吉思汗的孙子旭烈兀所取得的伟大胜利，助长了这一希望。旭烈兀是个佛教徒，而他的妻子是基督教徒。（两个并列句，表示转折关系）
3）其他译法 这类定语从句除上述两种正规、固定的翻译方法外，还有其他几种比较灵活的译法。我们可以把翻译简单定语从句的方法融会贯通，运用其中，如译成定语+句子成分，即把一个从句译成定语，另一个从句译成句子成分；或译成并列句（或句子成分）+状语从句，即把一个从句译成并列句或句子成分，另一个从句译成状语从句等。
