The present application provides a method for time division multiplex service protection. The method includes: on an OLT in a passive optical network, a working uplink port and a protection uplink port are set for a time division multiplex service and a protection group is created for the working uplink port and the protection uplink port; when a service flow protection for the time division multiplex service is triggered, the time division multiplex service flow is switched from the working uplink port to the protection uplink port, therefore realizing the protection for the time division multiplex service flow. The present application provides an uplink channel protection mechanism for important services in an access system, such as the time division multiplex service, which needs no protection switching protocol, and makes the service recovery time stand within 50 ms, thereby realizing fast and nondestructive recovery of the time division multiplex service.