Characteristics of growth and lipid accumulation of Scenedesmus obliquas were investigated under the condition of adding different concentrations of NaNO₃, K₂HPO₄·3H₂O, MgSO₄·7H₂O, FeCl₃·6H₂O, and Na₂CO₃ in urban sewage water for reducing the cost of microalgae cultivation and resource utilization of urban sewage water. Results show that phosphorus and carbon in urban sewage water can meet the needs of nature growth and lipid metabolism of microalgae and low nitrogen and high Fe⁺₃ concentrations are conductive to the accumulation of lipid. In addition, under the condition of adding NaNO₃ of 2. 25 g/L, K₂HPO₄·3H₂O of 40 mg/L, MgSO₄·7H₂O of 56. 25 mg/L, FeCl₃·6H₂O of 9 mg/L, and Na₂CO₃ of 15 mg/L in urban sewage water, Scenedesmus obliquas grows well and the biomass is 3. 04 g/L, which is 2. 8 times of the biomass under the condition of original wastewater. Using urban sewage water in the cultivation of microalgae can achieve the purposes of resource utilization of wastewater and lowcost cultivation of microalgae, which is of great significance for industrial production.