There is no required major for undergraduates, though many states do require that you complete a certain number of course hours in areas such as accounting, business or math. Because of the number of hours needed to complete the requirements, most students find it easiest to major in accounting.
Some people choose to major in accounting, while others pursue a different major entirely and complete the necessary course hours as added classes. But be careful: majoring in a subject completely unrelated to accounting may mean you'll have to spend more time and money in school than someone who streamlined her academic path. Some states require that all individuals, regardless of undergraduate major, complete a fifth year and attain a master's degree before becoming certified.
It is important that you verify the CPA requirements of the state where you intend to practice so that you can make the best use of your coursework in college.