The invention discloses a frequency synchronizing device of general-purpose sequence bus, with a message frame initial signal generated by a host computer terminal system as a reference time pulse, the device comprises a frequency eliminator for enabling the high-frequency signal to generate a frequency-locking signal by a frequency elimination of variable frequency eliminating times; a counting unit having a presetting pulse wave quantities for detecting the error between the pulse quantity and presetting pulse wave quantity of the frequency-locking signal under the reference frequency and forming a detection error value; and an operating unit for recording the detection error value and generating an error adjustment value by operation; an adjusting unit for receiving the error adjustment value and correspondingly generating a shared adjustment value, in order to control the frequency eliminator under the next reference frequency, the variable frequency eliminating times can be adjusted according to the error adjustment value at an interval of the shared adjustment value, thereby reaching the purpose of synchronizing frequency.