The invention provides a three-dimensional memory and a data operation method thereof. The memory includes: a substrate; a stack layer positioned on the substrate, wherein the stack layer includes a plurality of grid layers arranged at intervals in a direction perpendicular to the substrate; channel holes passing through the stack layers; channel layers inside the channel holes; and drain layers positioned on the channel layers, wherein each drain layer includes a top P-type region and a bottom N-type region that form a PN junction. According to the invention, a data operation mode is changedmainly by changing the structure of the drain layers, data erasing can be realized through the drain layers without high voltage, and data reading and data writing are convenient, thereby preventing damage to a device and prolonging the service life of the three-dimensional memory.