In order to apply to an MLS program, you’ll need an undergraduate degree from a college or university. There is no particular major requirement if you want to become a librarian, but common majors include English, Art History, Computer Science, and other courses of study that require research and technology skills. If you plan to become a librarian in a specialized library, such as a law or science library, you may need a secondary degree in a specific field. In this case, make sure you choose a major with classes that cover the prerequisites you’ll need for acceptance into a master’s program in your field. The ALA website, http://www.ala.org, is an excellent resource for information on MLS programs. You’ll find a directory of accredited programs with descriptions of each one.  Conduct a lot of research before you choose where to apply. Each program is quite unique; some focus on technology, others on the politics of information accessibility, and so on. Some programs require that you live on campus, while others are conducted entirely online. If you find out about a program through a source other than the ALA website, double check to make sure it’s ALA-accredited before going forward. Many libraries will not hire candidates with degrees from non-accredited schools. Some prestigious institutions offer programs on information technology that are not ALA-accredited. If you’re interested in information technology, but not necessarily in managing a library or the other responsibilities that being a librarian might entail, you may want to look into these alternatives.

TL;DR in Chinese:
获得本科学历。 （如果你申请的职位在美国）取得由美国图书馆学会认证的图书馆学硕士学位。