The invention discloses a method and device for updating a hardware access control list and a switch. The method includes the steps that when ACL rules are written fully in the hardware access control list, at least one neighbor request message is sent to host nodes corresponding to list entries in a software DHCPv6 binding list, and meanwhile a timer is started for the host nodes; at least one neighbor announcement message which is fed back by the host nodes and corresponds to the at least one neighbor request message is monitored; if the at least one neighbor announcement message fed back by the host nodes is not received before the timing of the timer is cut off, it is determined that the host nodes have been offline; when it is monitored that the host modes are offline, the ACL rules which are located in the ACL list and correspond to the offline host nodes are deleted. With the method and device for updating the hardware access control list, the utilization ratio of the ACL list of the switch is improved, and access requirements of more online hosts are met.