1. A system for recommending search input, comprising: a processor; and a memory communicatively coupled to the processor and storing instructions that upon execution by the processor cause the system to: obtain search keyword(s) according to a user input; query a search tree storage unit according to the search keyword(s) to obtain address information of recommended word(s), wherein the search tree storage unit is configured to store Chinese characters in a tree data structure, each data node in the tree data structure stores one Chinese character and address information of recommended word(s) containing the Chinese character; query a recommended word database according to the address information to acquire the recommended word(s) and then suggest the recommended word(s) to the user, wherein the recommended word database is configured to store recommended words; wherein the user input is Pinyin input or Chinese character(s) input; wherein when the user input is the Chinese character(s) input, the instructions that upon execution by the processor cause the system to obtain search keyword(s) according to a user input further comprise instructions that upon execution by the processor cause the system to: receive Chinese character(s) input by the user and use the input Chinese character(s) directly as a search keyword; the instructions that upon execution by the processor cause the system to query a search tree storage unit according to the search keyword(s) to obtain address information of recommended word(s) further comprise instructions that upon execution by the processor cause the system to: query the search tree storage unit to find address information of primary recommended word(s) with the input Chinese character(s) as a prefix at a node corresponding to the last character of the input Chinese character(s); judge whether the number of corresponding primary recommended word(s) is bigger than or equal to a preset threshold value according to the address information of the primary recommended word(s); and if yes, executing the operation of querying a recommended word database according to the address information of the recommended word(s) to acquire the recommended word(s) and then suggesting the recommended word(s) to the user; otherwise, querying the recommended word database based on the address information of the primary recommended word(s) to acquire the primary recommended word(s) and the memory further stores instructions that upon execution by the processor cause the system to: extend the primary recommended word(s) to acquire address information of the extended recommended word(s).