To enhance the production efficiency of short chain fatty acids (SCFAs) in anaerobic sludge fermentation reactor, sludge from another stabilized fermentation reactor (over 90 days) under pH 10 was seeded into the reactors to examine its effect on SCFAs production. Two sets of experiment were designed to investigate the SCFAs production with/without seeding sludge under pH=7.4±0.2 and pH=10±0.2, respectively. Experimental results showed that (1) under same pH condition, the maximum SCFAs accumulation with seeding sludge additive increased by 4.9 mg COD/g VSS (pH=7.4±0.2) and 16.4 mg COD/g VSS (pH=10±0.2) respectively, in comparison with the control reactors; (2) with two reactors with seeding sludge, the maximum SCFAs accumulation at pH 10±0.2 increased by 146.2 mg COD/g VSS as compared with the condition of pH=7.4±0.2; (3) the maximum SCFAs accumulation at pH 10±0.2 without seeding sludge was 129.8 mg COD/g VSS higher than that of pH 7.4±0.2 with seeding sludge. Overall, seeding sludge improved SCFAs production efficiency, meanwhile, seeding sludge under alkaline pH could play synergetic role in enhancing the SCFAs accumulation.