The invention discloses an embedded fault oscillograph suitable for DC control protection system. The fault oscillograph comprises a programmable logic controller, a microprocessor, a differential communication chip, a fault determining assembly and a first chip; the programmable logic controller is in communication connection with external equipment via the differential communication chip, obtains wave recording data of the external equipment via the differential communication chip, and writes the wave recording data into the first chip; the fault determining assembly determines whether thereis a fault in the external equipment, and if YES, a time point of the fault is determined; the programmable logic controller obtains wave recording data in the fault time point and within preset timebefore and after the fault time point via the first chip and further obtains the fault wave recording data, and the fault wave recording data is sent to the microprocessor; and the microprocessor generates a fault wave recording file according to the fault wave recording data. The fault oscillograph is high in integrate degree, reduces the equipment cost, and meets the light and compact trend forsecond equipment of the power system.