The utility model discloses a cold slewing device failure diagnosis of system instrument of HVDC valve, by signal acquisition module, signal synthesis processing module, failure diagnosis processing module of central authorities and man -machine interaction module connect the constitution in order. The signal acquisition module adopts a voice capture module, the 2nd voice capture module to constitute, monitor slewing device respectively before, terminal, with two way sound sound signal deliver to the signal synthesis module carry out prior art's filtering, fall make an uproar, weighted mean, deliver to failure diagnosis voice capture module 0 with the signal behind the output processing, failure diagnosis voice capture module 0 is according to the present simple program set for and voice capture module 3's the corresponding diagnosis of voice capture module 4 to with repayment as a result to man -machine interaction module. The utility model discloses simple structure, the equipment is convenient, has adopted a voice capture module, the 2nd voice capture module to constitute, monitor slewing device respectively before, terminal, such structure makes the judged result more accurate.