An input method comprises: A, classifying characters according to a preset rule, and displaying and outputting all of classification items (S101); B, expanding, according to a detected and triggered classification item, at least one character set corresponding to the classification item (S102); C, placing focus on a character set according to the detected and triggered character set (S103); D, and determining, according to the detected and triggered character of a current character set, an input character (S104). By configuring the classification item and the character set, the input method can achieve a simple selection input with respect to a large number of characters under limited operations, and improves user experience. Also disclosed are a corresponding electronic apparatus and input method thereof.