Memory connecting device, memory connector and mainboard

The invention discloses a memory connecting device, a memory connector and a mainboard, and belongs to the technical field of computers. A plurality of memory connectors are arranged on a circuit board of the memory connecting device for the same signal line, a pin of each memory connector can be connected with the signal line in a first state and does not make contact with the signal line in a second state, and when the pin of one memory connector is in the first state, the pin of the other memory connector does not make contact with the signal line in the second state. Under the condition that the pins of the remaining memory connectors are in the second state, the signal line is only connected with one memory connector, the positions, not connected with the memory connectors, in the signal line do not have impedance abrupt change, and when signals in the signal line are transmitted to the connected memory connectors, signal reflection caused by the impedance abrupt change can be avoided; the integrity of the signal is improved, and the data transmission bandwidth of the signal line is further improved.