Computing equipment extending method and device as well as extensible computing system

The invention discloses a computing equipment extending method and device as well as an extensible computing system. The equipment extending device comprises a first port, a second port and a third port, wherein the first port is connected with external computing equipment through a memory bus, the second port is connected with an external memory through a memory bus, the third port is connected with an external extended function unit through a user defined bus, and the equipment extending device generates a selection signal according to memory bus signals transmitted by computing equipment, so that any one port of the first to third ports is connected with one port in the rest two ports of the first to third ports, the routing function of the memory bus is provided, and the memory bus signals comprise data signals and control signals. The equipment extending device can use a standard memory bus and a memory slot, so the original computing system can be compatible, and in addition, the newly added function is provided at low cost.