Sunflower seed hulls (SSH) are agricultural waste from sunflower seed processing. Biodegradation of lignocellulosic waste using white rot fungi has been known as more harmless method than the chemical treatment, besides solving the environmental problems. The objective of this research was to investigate the effect of temperature, pH and nitrogen source on lignin degradation and ligninolytic enzyme production by Lentinus polychrous Lev. LP-SW-3 under solid-state fermentation of SSH for 30 days. Temperature at 35-40 oC and pH at 5.0-5.5 was the optimum condition for delignification and laccase production. The fungus potentially secreted manganese peroxidase (MnP) at 30-40 oC and pH 4.0-5.5, whereas low production of lignin peroxidase (LiP) was detected in all treatments. In addition, the high fungal growth was found at 30-40 oC and pH 5.0. Furthermore, a study on the addition of two nitrogen sources, including organic nitrogen (peptone and yeast extract) and inorganic nitrogen (KNO3 and (NH4)2SO4) during the fermentation at 35 oC was conducted. Adding 3 mM-N KNO3 resulted in the highest lignin loss and laccase production, whereas the highest MnP production was found by adding 2% peptone. However, low LiP production was detected in all treatments. The highest fungal growth was detected in the presence of 30 mM-N KNO3.