The invention discloses a dual-effect purification system for integrated treatment of coked fuel gas and ammonia containing wastewater. The dual-effect purification system comprises a desulfurization and denitrification tower and an ammonia still, wherein the desulfurization and denitrification tower is connected with a fuel gas reboiler; a fuel gas reheater is arranged on a flue gas pipeline I; the lower part of the ammonia still is connected with a pipeline in the fuel gas reboiler; the desulfurization and denitrification tower is connected with the flue gas reheater and the ammonia still; the ammonia still, a dephlegmator and a total condenser are sequentially connected; the bottom of the total condenser is connected with an ammonia water reflux tank; the ammonia water reflux tank is connected with the desulfurization and denitrification tower; an ammonia water sprinkling structure is arranged at the upper part inside the desulfurization and denitrification tower; a circulating pump is respectively connected with the bottom of the desulfurization and nitrification tower and the ammonia water sprinkling structure. According to the dual-effect purification system disclosed by the invention, flue gas is desulfurized and purified by using a wastewater ammonia source, wastewater is ammonia-removed and purified by using the flue gas, and wastes are treated by using waste resources inside a coking process, so that the cost is low, escape of vapor-phase ammonia is reduced, pH value of a desulfurizing solution is adjusted by using concentrated ammonia water for ammonia stilling, controllable implementation of desulfurization and denitrification is realized, and a purification effect is remarkably improved.