The invention discloses a multiple-to-one VLAN projection method, comprising that (1), dividing each VLAN of descending port into N regions, while N is integer larger than 1, and each region comprises a plurality of VLAN, (2), a data pack entering into the ascending port of VLAN projection, according to character learns MAC and searches a MAC list, (3), when MAC can not be searched in the step (2), a network processor copies the data pack into N portions, while each portion is relative to a descending VLAN region, (4), the network processor copies each data pack copied in the step (3), while the copied number is the VLAN number contained in each region, to complete the broadcast of data pack in descending port. The inventive method can improve data transmission efficiency, and break the limitations on range and number of descending port VLAN, to support the expansion of descending port.