The effects of sulfonamides on soil respiration, nitrification, ammonification, ammonium, nitrate, nitrite nitrogen and total nitrogen were studied. The results showed that lower concentration of drug residue (10 mg/kg soil) on soil respiration showed the law of ‘activation – inhibition’, the higher concentration of drug residue (50 mg/kg soil) on soil respiration showed the law of ‘restraint - activation - inhibition’, which proved that sulfonamides could inhibit soil respiration. Lower concentration of drug residue (10 mg/kg soil) on soil nitrification and ammonification showed the law of ‘activation – inhibition’, higher concentration of drug residue (50 mg/kg soil) on soil nitrification and ammonification showed the state of ‘activation’, which proved that sulfonamides could stimulate soil nitrification and ammonification. Nitrogen is an important indicator of biosphere nitrogen cycle, sulfonamides drug residue on soil nitrogen had some inhibitory effect, and a high residue level of long-term will destroy soil nitrogen cycle.