The invention provides a method for opening or closing an intelligent door lock through a block chain. The method comprises the steps that a processor of a computing system generates an access code and a private key associated with the access code, wherein the access code is used for obtaining access to the intelligent door lock; the processor performs hash on the access code to obtain a hash access code; the processor uses a public key to encrypt the hash access code so as to create a digital signature, wherein the hash access code and the digital signature are stored in the block chain; theprocessor authenticates an intelligent mobile terminal in response to a request of accessing the intelligent door lock from the intelligent mobile terminal; the processor sends the private key and thedigital signature to the authenticated intelligent mobile terminal; the authenticated intelligent mobile terminal uses the private key to decrypt the digital signature so as to obtain the hash accesscode, and sends the hash access code to the computing system; and in response to the condition that the hash access code is received from the intelligent mobile terminal, the processor controls the intelligent door lock to open or close the intelligent door lock.