The invention discloses a method for automatically detecting an earthquake auxiliary channel. The method for automatically detecting an earthquake auxiliary channel includes the following steps that data of a reference signal channel and data of a verification earthquake auxiliary channel in a time selection window of a corresponding clock earthquake auxiliary channel are read from an earthquake record database; according to the data of the reference signal channel and the data of the verification earthquake auxiliary channel, the hopping point time of a first impulse of the reference signal channel and the hopping point time of a first impulse of the verification earthquake auxiliary channel are calculated respectively; the time difference between the hopping point time of the first impulse of the reference signal channel and the hopping point time of the first impulse of the verification earthquake auxiliary channel is calculated and the time difference is compared with a specified time difference; if the time difference is larger than the specified time difference, a synchronization abnormality of an earthquake collecting and recording system is indicated.