Provided are a routing lookup method and device, and a method for constructing a B-Tree structure, wherein the device includes a routing lookup algorithm software component, a routing update interface component and a routing lookup hardware component, the routing lookup algorithm software component is configured to execute software calculation for a routing entry and issue an entry update instruction, the routing update interface component is configured to control, after receiving the entry update instruction issued by the routing lookup algorithm software component, a data stream of the routing lookup hardware component according to an actual working state of the routing lookup hardware component, and write an updated entry into a memory of the routing lookup hardware component, and the routing lookup hardware component is configured to respond to a routing lookup request of a hardware system, and return a lookup result matched with a longest prefix to the hardware system.