An unlocking method for an intelligent door lock, a mobile terminal, an intelligent door lock and a cloud server. The method comprises: a mobile terminal receiving an initial key and a communication key from a cloud server (S101a); the mobile terminal encrypting the initial key and pre-set key data by using the communication key, so as to generate an unlocking verification code (S102a); the mobileterminal adding the pre-set key data to the unlocking verification code, and obtaining the unlocking verification code with the pre-set key data added thereto (S103a); and the mobile terminal sendingthe unlocking verification code with the pre-set key data added thereto to the intelligent door lock, so that the intelligent door lock performs unlocking according to the unlocking verification codewith the pre-set key data added thereto (S104a). An initial password and pre-set key data are encrypted by using a communication key, so as to generate an unlocking verification code, and the initialkey and the communication key can be prevented from being tampered with by means of the transmission of the unlocking verification code, thus guaranteeing the security of unlocking an intelligent door lock and avoiding property damage.