A device for improving an item access bandwidth and atomic operation, comprising: a comparison module , a cache , and a distribution module , wherein the comparison module is arranged to: after a lookup request is received from a service side, determine whether an address pointed to by the lookup request is identical to an item address stored in the cache ; if they are identical, and a valid identifier vld is currently valid, directly return item data stored in the cache to the service side without initiating a request for looking up an off-chip memory, so as to reduce accessing the off-chip memory; and if they are not identical, initiate a request for looking up the off-chip memory, and process, according to a preset rule, item data returned by the off-chip memory in such a way that an atomic operation existed in item updating can realize a seamless and faultless lookup in an item lookup process; the cache is arranged to store the item data and the item address; and the distribution module is arranged to identify whether data to be returned to the service side is the item data in the cache or the item data in the off-chip memory, and then return the data to the service side, characterized in that the comparison module is further arranged to determine, according to the first preset rule, whether the address pointed to by the lookup request is identical to the address stored in the cache , comprising any one of the following ways: way 1: if a vld corresponding to a low first-threshold-M bit address is completely valid, and a high second-threshold-N bit address is identical to the address stored in the cache , returning data in the cache to the service side, and not updating the data in the cache ; if the addresses are not identical, not updating the data in the cache , and sending the data returned by the off-chip memory to the service side; way 2: if the vld corresponding to the low first-threshold-M bit address is partially valid, not updating the data in the cache , and sending the data returned by the off-chip memory to the service side; and way 3: if the vld corresponding to the low first-threshold-M bit address is invalid, updating the data in the cache , and sending the data returned by the off-chip memory to the service side; wherein both M and N are natural numbers, and the sum of M and N is a bit width requested by the service side. way 1: if a vld corresponding to a low first-threshold-M bit address is completely valid, and a high second-threshold-N bit address is identical to the address stored in the cache , returning data in the cache to the service side, and not updating the data in the cache ; if the addresses are not identical, not updating the data in the cache , and sending the data returned by the off-chip memory to the service side; way 2: if the vld corresponding to the low first-threshold-M bit address is partially valid, not updating the data in the cache , and sending the data returned by the off-chip memory to the service side; and way 3: if the vld corresponding to the low first-threshold-M bit address is invalid, updating the data in the cache , and sending the data returned by the off-chip memory to the service side; <EOS>