Based on low carbon wastewater as the research object and using corncob as an external solid carbon source, the performance of corncob organic matter was assessed for its release potential, quantity of release, and safety of use. The effects of varying quantities of the solid carbon source on simultaneous nitrification and denitrification were investigated in a sequencing biofilm batch reactor (SBBR). Results show that the regularity of corncob as solid carbon source material was linear, with released concentrations of heavy metals being below the Chinese national standard limit values for heavy metals according to the surface water environment quality standards (I and II) (GB3838-2002). When temperatures were within 28~31°C, the dissolved oxygen level was 4.0 ± 0.2 mg/L and the pH conditions were within 7.5~8.0. The optimal quantity for corncob dosing was 5 g per 1.5 L of low carbon wastewater. Following treatment, the average effluent concentrations of NH4+-N and TN were 2.85 mg/L and 4.51 mg/L, respectively. The effluent concentration of NH4+-N, TN had reached the A level national standard of sewage treatment plant pollutant discharge standard (GB18918-2002).