坛子里不少哥们儿姐们儿关心这个，那就把国际足联的官方文件贴出来大家看看就知道了，以下是FIFA的官方文件关于球员选择更换效力国籍的部分，都是很通俗的英文，大家一看就懂了
第一部分（17）是关于球员如何获得另一国国籍的
第二部分（18）是关于球员如何更换效力国籍的
17 Acquisition of a new nationality
Any Player who refers to art. 15 par. 1 to assume a new nationality and who
has not played international football in accordance with art. 15 par. 2 shall
be eligible to play for the new representative team only if he fulfils one of the
following conditions:
(a) He was born on the territory of the relevant Association;
(b) His biological mother or biological father was born on the territory of
the relevant Association;
(c) His grandmother or grandfather was born on the territory of the
relevant Association;
(d) He has lived continuously for at least five years after reaching the age
of 18 on the territory of the relevant Association.
18 Change of Association
1. If a Player has more than one nationality, or if a Player acquires a new
nationality, or if a Player is eligible to play for several representative teams
due to nationality, he may, only once, request to change the Association for
which he is eligible to play international matches to the Association of another
country of which he holds nationality, subject to the following conditions:
(a) He has not played a match (either in full or in part) in an official
competition at “A” international level for his current Association, and at
the time of his fi rst full or partial appearance in an international match
in an offi cial competition for his current Association, he already had the
nationality of the representative team for which he wishes to play.
(b) He is not permitted to play for his new Association in any competition
in which he has already played for his previous Association.
2. If a Player who has been fielded by his Association in an international
match in accordance with art. 15 par. 2 permanently loses the nationality
of that country without his consent or against his will due to a decision
by a government authority, he may request permission to play for another
Association whose nationality he already has or has acquired.
3. Any Player who has the right to change Associations in accordance with
par. 1 and 2 above shall submit a written, substantiated request to the FIFA
general secretariat. The Players’ Status Committee shall decide on the request.
The procedure will be in accordance with the Rules Governing the Procedures
of the Players’ Status Committee and the Dispute Resolution Chamber. Once
the Player has fi led his request, he is not eligible to play for any representative
team until his request has been processed.
翻译：
15章： 基本原则
1. 球员可以为其永久国籍所在的国家效力，此项原则不受其居住国家或地区的影响
2. 除了在18章中特别提到的限制外，任何球员如果已经代表某国家在国际足联官方承认的任意级别的非友谊赛中出场（首发或者替补）将没有资格再为另一个国家效力
17章： 如何获得新的国籍
任何满足15章第一部分要求以及还没有在任何15章第二部分提到的比赛中出场的并且想要为另一个国家效力的球员必须满足以下条件中的至少一个：
(a) 在该国家的领土中出生
(b) 血缘关系上的父母（非养父母）中的至少一位是在该国家的领土中出生
(c) 血缘关系上的祖父母或者外祖父母中的至少一位是在该国家的领土中出生
(d) 在该国家连续生活时间达到至少五年（从18岁开始算起）
18章： 如何更换效力国籍
1. 任何多国籍球员，或者获得新的国籍的球员只有一次机会选择为另一个国家（必须拥有该国国籍）效力，并且必须满足以下条件：
(a) 该球员还没有在国际足联的任意官方A级非友谊赛级别的比赛中为其当前的国家出场（首发或者替补）， 在其第一次为希望更换的国家出场时（必须为国际足联官方非友谊赛，首发或者替补），该球员必须已经获得该国国籍
(b) 该球员一旦已经为之前效力国家在非友谊赛中出场，他将不再被允许为另一个国家在任何非友谊赛中出场
2. 任何因为政府强行征调而违反15章第二部分的球员，不管其本人意愿如何都将永久失去为该国效力的资格，但同时他可以申请为另一个其拥有国籍的国家效力
3. 任何想要更换效力国籍并且满足以上条件的球员必须向国际足联总秘书长提交一份具体的书面证明，球员身份仲裁委员会将将根据相关法规决定是否批准该申请，该球员一旦提交申请，在有任何结果出现之前将没有资格代表任何国家出场
另外注明一下：
competition A match: 指非友谊赛的洲际级别比赛，包括世界杯或者洲际杯的预选赛和正赛
另外这里的国籍我认为是指足球范畴内的国籍 |
楼主