The invention discloses a concentration and crystallization process for ammonium sulphate waste liquor, and relates to the technical field of chemical industry production, in particular to technology for preparing ammonium sulphate crystal from the ammonium sulphate waste liquor through concentration. The process comprises the following steps of: heating 1 to 20 percent ammonium sulphate waste liquor to between 55 and 75 DEG C; pumping the ammonium sulphate waste liquor into a crystallizer; concentrating the ammonium sulphate waste liquor in the crystallizer through evaporation; pumping part of 40 to 50 percent solution into a crystal paste tank through a discharging pump to perform crystallization; separating the crystal by using a centrifugal machine after the crystal is grown up; allowing the residual mother liquor to enter a head tank to continuously perform the evaporation circulation; compressing and heating the secondary steam evaporated by the crystallizer by using a compressor; leading the steam downwards into the shell side of a heater to exchange heat with materials in the heater; and obtaining condensed water by condensation. The process can achieve good evaporation effect by using a small amount of electric energy, thereby developing a new way for cost reduction and energy conservation during the treatment of the ammonium sulphate waste liquor.