美国护照三个月有效期就够了 U.S. Citizenship holders You are allowed to travel to Italy and to all other members of the Schengen Area for up to 90 days for tourist or business purposes without a visa, as long as your U.S. passport is valid for at least 3 months after your planned return to the United States!
欧盟的规定是护照在预定离开时要有三个月有效期， 文件在此： Article 6 Entry conditions for third-country nationals 1. For intended stays on the territory of the Member States of a duration of no more than 90 days in any 180-day period, which entails considering the 180-day period preceding each day of stay, the entry conditions for third-country nationals shall be the following: (a) they are in possession of a valid travel document entitling the holder to cross the border satisfying the following criteria: (i) its validity shall extend at least three months after the intended date of departure from the territory of the Member States. In a justified case of emergency, this obligation may be waived; (ii) it shall have been issued within the previous 10 years; https://eur-lex.europa.eu/eli/reg/2016/399/oj
有绿卡，这样回得来美国吗
不行的话得赶快去换护照了，欧洲签证得用新护照签
不是的，特意查过，美国护照也需要六个月有效期，刚从意大利回来
不是的，不少地方不需要6个月，有些地方完全没要求。不过楼主有时间就换一下吧，普通的也不到一个月就收到了
你需要查你去的欧洲国家入境时对护照有效期的规定，回美国有绿卡，护照有效期不是问题（按美国规定，有绿卡，护照失效都能入境，但如果航空公司不了解政策，不让你登机，那就没办法了）。
拿到签证之后更新护照，签证并不会作废只要签证页没有损伤，到时候需要新旧护照一起出示使用。
入美国不需要，绿卡对美国政府来说就是充分的有效旅行证件，但是为了保险还是得有护照，因为美国政府不能强制其它国家或者航空公司承认绿卡是充分证件。
常规操作 如果不给护照要去小黑屋一趟 验证完会放进来 但是耽误时间
不要想当然 每个出境国和入境国的规定都不一样的 机场航空公司的柜台电脑都有一个系统 可以按证件签发国和类型以及目的地查询入境要求