Disclosed is a low-mercury catalyst for acetylene hydrochlorination. Mercuric chloride is carried on activated carbon. Raw materials comprise, by weight, 100 parts of activated carbon, 4-5 parts of mercuric chloride, 8-10 parts of total essential assistant, 1-5 parts of total non-essential assistant, wherein the essential assistant comprises 2-5 parts of bismuth chloride, 1-5 parts of cerium chloride, 1-5 parts of barium chloride and 2-5 parts of copper chloride; and the non-essential assistant comprises at least one of potassium chloride, phosphoric acid, zinc chloride and cuprous chloride. After being subjected to surface subtraction and drying on acid and oxidizing conditions, activated carbon is in reflux treatment with urea solution; and the catalyst can be prepared by soaking the treated activated carbon with HgC12 dissolved in hydrochloric acid and assistant solution sufficiently after urea is removed by steps of heating, washing the activated carbon with hydrochloric acid and finally drying the same. The carrying capacity of mercuric chloride in the catalyst is lower so that cost for the catalyst is reduced and consumption of mercury resources is decreased. Furthermore, activity and stability of the low-mercury catalyst are much higher than those of the existing high-mercury catalyst, and reforming rate and selectivity of reaction of vinyl chloride can be 99.7% and be higher than 99.8%. Accordingly, the low-mercury catalyst for acetylene hydrochlorination is suitable for industry production and is environment-friendly.