A method and an apparatus for adjusting an input/output (I/O) channel on a virtual platform, and the method for adjusting an I/O channel includes: counting, by a host, current average I/O throughput of multiple virtual machines (VMs) operating on the host; increasing or decreasing, by the host, working threads for processing the VMs between front devices and back devices of the multiple VMs according to the current average I/O throughput; and adjusting, by the host, a mapping relationship between queues in the front device, queues in the back devices of the multiple VMs, and working threads for processing the VMs. According to the present invention, when the I/O throughput decreases, idle I/O channel resources are released, thereby avoiding a waste of the I/O channel resources; when the I/O throughput increases, the I/O channel resources are increased, resulting in an improved data transmission capability of the I/O channels.