The use of abundant sunlight for semiconductor photo-degradation of antibiotics is an ideal way to solve global water pollution. Here, the sodium nitrate modified photocatalysts exhibits enhanced photocatalytic efficiency for degradation of tylosin under simulated sunlight irradiation over g-C3N4 alone. In addition, the pure g-C3N4 and sodium nitrate modified g-C3N4 photocatalysts were investigated in terms of their crystal structures, morphologies, optical properties by using XRD, SEM, TEM, Raman, FTIR, UV-vis and XPS. On the basis of these. results, the morphology dependence of the visible light absorption and the photocatalytic efficiency under simulated sunlight irradiation has been systematically investigated. It was found that the type of precursors and the molar ratio of sodium nitrate have an evident impact on the crystal structure of g-C3N4, and photocatalytic performance due to varied reaction pathways and degree of condensation. The photocatalytic activity evaluated under simulated sunlight indicates that the as-synthesized photocatalysts is effective in obtaining the energy of solar spectrum and transforming it into the chemical energy for tylosin degradation.