The invention relates to a low-power-consumption preamble resource allocation method for a machine type communication system. The method has the advantages that under the condition that physical random access channels are limited, according to the principle of ''the maximum access efficiency'' and through spatial cell grouping, preamble resources are added, and access control and preamble resource allocation are independently carried out on each group, so that the access efficiency is improved, the power consumption for access is reduced, and the applicability for a low-consumption machine type communication scene is achieved.