The invention discloses a block device thin-provisioning method for log mapping. The method comprises the step of hard disk data distribution, wherein storage resources are formatted, and resource pooling management is carried out on hard disk data distribution so as to support thin-provisioning resource allocation and storage and management of log mapping information, the step of thin-provisioning resource management, wherein on the basis of a hard disk with pooled resources, the data are sequentially written into a next free resource of the hard disk in a writing on-demand allocation mode of the storage resources, and mapping information corresponding to write operation is generated; the step of mapping information logging, wherein logging storage is carried out on the mapping information of the write operation according to an additional allocation mode, and on the basis of an asynchronous updating mode, the mapping information is amended so as to achieve data writing of the multi-user and multi-virtual-volume concurrence sequence.