The invention provides a nickel-chromium-cobalt-molybdenum heat resisting alloy and a pipe manufacturing process thereof and belongs to the technical field of the heat-resisting alloys. The alloy comprises the following chemical components in percentage by weight: 21-23% of Cr, 0.05%-0.07% of C, less than or equal to 0.3% of Mn, 11-13% of Co, 6.0-9.0% of Mo, 0.3-0.5% of Ti, 0.8-1.3% of Al, 0.1-1.0% of W, 0.002-0.005% of B, 0.03-0.15% of Zr, 0.2-0.6% of Nb+V and 0.01-0.05% of Nb, less than or equal to 0.15% of Cu, less than 0.008% of P, less than 0.002% of S, less than or equal to 0.015% of N, 0.005-0.02% of Mg, less than or equal to 0.01% of Ca, less than or equal to 0.01% of As, less than or equal to 0.07% of Pb, less than or equal to 0.001% of Bi and the balance of nickel and inevitable impurity elements. The nickel-chromium-cobalt-molybdenum heat resisting alloy has the advantages that the room-temperature mechanical properties, the high-temperature mechanical properties, the low cycle fatigue properties and the durability of a large-diameter thick-wall boiler pipe produced from the nickel-chromium-cobalt-molybdenum heat resisting alloy are all over ASME standard requirements and the technical requirements of CCA617 alloys; the formulation of HAZ liquation cracks and stress relaxation cracks is greatly reduced, and the HAZ long term rupture strength and the tenacity after long term aging both are excellent.