Ammonia is one of the most significant contaminants of water resources which make perilous and dire environmental detriment for human life. In this investigation, the photocatalytic degradation of ammonia from an aqueous solution was evaluated with the help of titania nanoparticles. Titania nanoparticles (NPs) were synthesized by sol-gel procedure and also the surface morphology and chemical structure of them was carried out by XRD(X-ray powder diffraction), FTIR(Fourier transform infrared), DLS(Dynamic light scattering), EDX( Energy-dispersive X-ray spectroscopy), FE-SEM(field emission scanning electron microscope), and TEM(Transmission electron microscope) analyses. To elaborate the effect of some parameters including pH, initial concentration of pollutant, catalyst dosage and contact time, Design Expert Software (I optimal technique) was employed. Results demonstrated that titania NPs have a high photocatalytic activity for ammonia removal. Moreover, the pH parameter had the greatest effect on the degradation performance. The optimum amounts of NPs concentration, initial concentration of contaminant, contact time and pH obtained 0.3 g/l, 1500 mg/l, 120 min and 12. NPs were used four times and results showed that the removal efficiency of the NPs decrease from 96.96 % to 65%.