Abstract: In this paper,a series of the pulse-type carbonitriding experiments under low vacuum condition have been conducted in a self-made multipurpose chemico-thermal treatment furnace.The effects of the impregnant compositions and the doses thereof,the working pressure,the pulsing cycles,the treatment temperatures,and the treatment time on the properties of the impregnated layers have been studied.Results have shown that this kind of traetment,if under proper technological conditions,is ahle to satisfy the requirements as follows:layer depth 0.1～0.3mm,hardness≥58HRC.