A random access method, an apparatus, and a system are disclosed. A terminal device receives, from a network device, information about a PRACH resource set and information about one or more PUSCH resources associated with each PRACH resource in the PRACH resource set. If a first PUSCH resource associated with a valid first PRACH resource in the PRACH resource set is valid, the terminal device sends a first preamble sequence to the network device on the first PRACH resource, and sends uplink data to the network device on the first PUSCH resource. The network device receives the first preamble sequence from the terminal device on the first PRACH resource, and receives the uplink data from the terminal device on the first PUSCH resource. The first preamble sequence is a preamble sequence set associated with the first PUSCH resource.