The invention relates to metallurgical industry, and provides a Ni-based high temperature alloy for a pyrolyzing furnace pipe, which comprises the following chemical components in percentage by weight: 0.40 to 0.60 percent of C, 1.00 to 1.80 percent of Si, 0.80 to 1.50 percent of Mn, less than 0.03 percent of P, less than 0.02 percent of S, 34.00 to 37.00 percent of Cr, 43.00 to 47.00 percent of Ni, 0.80 to 1.50 percent of Nb, less than or equal to 0.5 percent of Mo, 0.02 to 0.20 percent of Zr, 0.02 to 0.20 percent of Ti, 0.02 to 0.20 percent of Ce, and the balance of Fe and trace impurities.The Ni-based high temperature alloy for the pyrolyzing furnace pipe overcomes the disadvantages of cracking, large heat deformation, poor anti-carburizing capacity, susceptibility to coking, bulging and the like of pyrolyzing furnace pipes made of the prior HK40 or HPNb material, and is mainly used for manufacturing petrochemical ethylene cracking furnace radiation room furnace tubes and other high temperature devices.