The present invention discloses a probe expanding device of electronic equipment and a method for controlling expanding probe by the host machine, wherein the device comprises a body and a probe expanding device plug. The body is provided with a controller, a probe signal commutation circuit, a first probe socket, a second probe socket and a probe expanding device plug. A host machine determines whether the reading of expanding probe is finished and enquires the on-position state of probe through a controller of probe expanding device. The probe which is to be executed with information reading transmits a power supply enable signal through a controller for supplying power to the corresponding probe. The communication interface of corresponding probe is gated for reading probe information.When the host machine confirms that the probe information reading is finished, a probe de-electrifying command is transmitted to the controller by the host machine. The controller controls the power supply enable signal. The corresponding probe is de-electrified and the operation is finished. An interface communication connection is realized between the probe expanding device and the host machinedevice according to the invention. An inner controller analyzes command of host machine system and realizes the functions of probe identifying, working probe switching, etc. The control to various functions is conveniently and reliably executed. The automatization degree of operation is high.