The embodiments of the present invention provide an interleave-based method and apparatus for enhancing capacity of a random access channel, wherein the method is applied to a terminal device. The method includes: receiving a set of preamble sequences and at least two interleavers sent by a base station; determining, when a random access is triggered, a to-be-used preamble sequence from the set of preamble sequences as a target preamble sequence, and randomly determining a to-be-used interleaver from the at least two interleavers as a target interleaver; performing interleaving processing on the target preamble sequence by using the target interleaver to generate an interleaved target preamble sequence, wherein, performing interleaving processing on the same preamble sequence by using different interleavers will generate different interleaved preamble sequences; sending a random access request to the base station by using the interleaved target preamble sequence. Applying the embodiments of the present invention can increase the number of available preamble sequences and increase the capacity of the PRACH.