The invention discloses a method and system for treating high-ammonia nitrogen photovoltaic waste water containing cadmium and thiourea. The high-ammonia nitrogen photovoltaic waste water containing cadmium and thiourea enters a primary comprehensive cadmium removing pool, NaOH, PAC and PAM are added in order for carrying out a coagulation reaction, cadmium precipitates are added into the waste water, NaOH is added for adjusting a pH value and the waste water enters a distillation stripper, and at the same time ammonia nitrogen in the waste water is recycled and converted into 16-19% ammoniacal liquor; effluent enters a secondary integrated cadmium removing pool, NaOH, TMT, PAC and PAM are added in order for carrying out a coagulation reaction, and a secondary treatment is carried out for residual cadmium substances in water; effluent enters an advanced oxidation pool, agent H2SO4, FeSO4, H2O2, and NaClO are added in order, and oxidation and decomposition are carried out for thiourea substances and residual ammonia nitrogen in the waste water; effluent enters a coagulative precipitation tank, agent NaOH, TMT, PAC and PAM are added in order, residual cadmium in water and oxidation products in the advanced oxidation technology are removed, and water quality of discharged water reaches a B grade standard in 'wastewater quality standards for discharge to municipal sewers' (GJ343-2010).