The utility model relates to an intelligent building access control system based on internet belongs to building access control system field, including unit door taboo, communication bus, bus serial port converter, server, compare with prior art, the utility model provides an enough connecting communication buses of an arbitrary unit door forbidden energy among the access control system, all insert unit door on the communication bus prohibit can both be connected to bus serial port converter on, during the server was sent into to data that bus serial port converter prohibits all received unit door, the transmitter data can backward be prohibited to unit door to the server, can prohibit by unit door 0 unit door, realizes the operation to fingerprint data, unit door switch. Unit door prohibits except fingerprint control door lock switch, can also go into the break -make of the parallel chip extension mouthful cascaded analog switch control relay of operation and then the control unit entry calling subscriber and the talk line of resident family through the cluster, has lower consumption simultaneously, and the stand -by power consumption is less than 1.35W, peak value low power dissipation in 2.25W.