Abstract: The nano-scale marble electrode was made,which conventional micron-scale marble in the coating of D600R,a hardfacing shielded metal-arc welding electrode,was replaced by nano-scale marble (CaCO₃) with particles size ranges of 70-90 nm. The welding current,arc voltage and short-circuiting time were measured with an arc characteristics analyzer (Hannover analystor),and the arc characteristics of the micron-scale marble and nano-scale marble electrodes were obtained. By means of welding procedure test,hydrogen test,melting temperature and hardness measuring,wear test and micro-analysis,the welding processing properties and mechanical properties of deposited metal of the two electrodes were studied respectively. The results show that when micron-scale marble is replaced by nano-scale marble,the melting temperature of coating and the amount of diffusible hydrogen in deposited metal are decreased,and the deposition efficiency of electrode is increased; the probability density sum of short-circuiting voltage and short-circuiting current,and the sum of short-circuiting time,including over 2.05 ms,are all decreased,and the electrode operating properties are improved; the hardness and wear resistance of deposit metal are enhanced.