Embodiments of the invention relate to the technical field of mobile terminal software systems, in particular to a method and terminal for encrypting local data. The method comprises the following steps of: receiving an encryption request of an application program by the terminal, wherein the encryption request comprises an identifier of the application program; obtaining first key source data from a dynamic link library of the terminal according to the identifier of the application program, wherein the first key source data is at least one expression which is determined according to a randomly generated first character string; obtaining second key source data, wherein the second key source data is determined according to a unique identifier of the terminal; and taking the first key source data and the second key source data as a key, and encrypting the local data by adopting an encryption algorithm. The first key source data of the key is randomly generated and the storage form of the key is an expression after decomposition but not a constant, so that the complexity of obtaining the key is improved and then the security of the key is enhanced.