The invention relates to a ferrochrome ferrite stainless steel welding and post-welding annealing technology in a cold continuous rolling production line, belongs to the technical field of cold continuous rolling production lines of ferrochrome ferrite stainless steels, and aims at solving the technical problems of belt breaking accident. The technology comprises the steps of (1), performing a welding process on ferrochrome ferrite stainless steel in the cold continuous rolling production line, namely, performing CO2 laser welding, and setting the welding technology parameters as that the laser power is 8-12kW, the welding speed is 12.0-3.4m/min, the clearances between weld joints are 0.10-0.33mm, the wire feeding speed is 1.13-10.58m/min, and the annealing power is 22.1-40.0kW; and welding the front parts and the rear parts of a front steel coil and a rear steel coil; and (2) performing annealing process after welding, namely, cooling by air for 2s after welding in step (1); and thencooling the upper surface and the lower surface of each weld joint for 2-7s through an upper cooling spraying pipe and a lower cooling spraying pipe. According to the technology, the annealing is rapidly carried out after welding, so that sigma phase in the weld joint structure can be reduced; and meanwhile, the temperature of embrittling under high temperature is reduced; the requirement of continuous rolling machine with more than 70% of weld joints having rolling deformation rate for plasticity and toughness can be met; and the belt breaking accident is avoided.