移民签证需要什么？
通常的移民签证是B1/B2 (tourist and business visitor) visa， 有效期是10年. 持此类签注入境后，在美国停留期间可以旅游或者从事商务活动（不能工作）.在离开美国后，可以再次申请此类的签证进入美国.
如果人在第三国，比如在中国，要申请来美签证，通常的流程是先向美国的使领馆提交材料，等待面谈的时间，然后去面谈. 如果通过的话，大使馆会在护照上盖章批准签证，并且把护照寄回给你. 如果是被拒签了的话，也会退回来，并在护照上贴上拒签条. 申请人需要亲自到指定的美国使领馆递交申请．目前中国的北京， 上海和广州都有使领馆，可以分别向美国4个州的居民发放签证. 北京领事馆管中国北部(包括东北三省和北京，天津)的居民， 上海领事馆管华东地区(浙江，江苏，上海和安徽)的居民， 而广州领事馆管华南地区和海南以及大多数的西南省份的居民．
除了必须准备的材料之外，申请不同种类的签证所需要的材料也有区别，而面签时考官的问题也可能因人因地而异，这些都不是本文可以涵盖的．所以请参阅所要申请的使领馆网站上的具体要求． 一般来说，面签时需要准备以下材料： • I-539 form， also called the "petition for re-entry of permanent resident" (for immigrants who did not leave US before their departure became effective); or， • Form I-94W (for Chinese citizens applying as nonimmigrants at a U.S. port-of entry)， both to be filled out by the applicant him/herself in block letters on white paper with black ink pen; these forms can be obtained from your local U.S. consulate， embassy or at the website mentioned above.
• Passport or travel document valid for at least six more months after arrival date. Note that some countries do no issue passports valid beyond this period， such as China；the only passport available is the so-called old style passport which has validity longer than six months but contains less information about owner's personal details; applicants are advised to go through the interview process ahead of time if possible and ask for clarification when asked whether they have any doubts about their documents， especially those whose passports expire within one year. If you have been married previously and are filing jointly，you should bring proof of divorce or death of previous spouse， including court decree and copy of last page of death certificate; If you filed separately during earlier application，please present the petitioner's original Form I-797 Approval Notice and photocopy of it for verification purposes. Also required are：
• Proof of financial support， ie， bank statement indicating sufficient funds，letter from employer showing regular employment history and salary information， etc; 也可以出示有足够价值的财产证明，比如房产证等，具体参考所申请的使领馆的要求