The invention provides a method for manufacturing unleaded brass easy to cut, a method for manufacturing a balance weight and a cooling device, and belongs to the technical field of alloy treatment. The problem that existing unleaded brass easy to cute is not suitable for being used for manufacturing compressor balance weight blanks through hot forging or warm forging or warm extruding or cold extruding is solved. The method for manufacturing the unleaded brass easy to cut comprises the steps that unleaded brass is firstly cooled to -170 DEG C to -196 DEG C, and then subjected to heat preservation; and the unleaded brass is slowly heated to 0 DEG C or above. The method for manufacturing the balance weight comprises the steps that a balance weight blank is firstly formed through hot forging or warming forging or warming extruding or cold extruding; then the balance weight blank is treated sequentially through a recrystallization annealing process and the method for manufacturing the unleaded brass easy to cut; and finally the balance weight blank is machined into the finished balance weight. The unleaded brass adopted in the balance weight is suitable for hot forging forming or warming forging forming or warming extruding forming or cold extruding forming, the relative content of the unleaded brass in the beta phase is effectively improved by cooling the balance weight blank, and the cutting performance of the balance weight blank is improved.