Based on sludge specific resistance as the evaluation index, considering the sludge dehydration rate, filter cake moisture content and filtration time. To investigate the optimum condition of sludge conditioning with chitosan and diatomite, and the effect of improving sludge dewatering performance,and compared with the effect of polyacrylamide sludge conditioning. Results showed that first dose 0.5 g/g of diatomite recuperate sludge, add the 5 mg/g of chitosan with 30 r/min stirring speed to reaction in 150 s, sludge specific resistance decreased by 95.43%, dehydration rate rose to 91.02%, moisture content of sludge cake down to 83.13%, the filtering time dropped to 29.5 s.The effect of chitosan combined with diatomite recuperate sludge was significantly superior to that of independently conditioning by chitosan or diatomite, and the effect of combined conditioning improving overall performance of sludge dewatering was superior to that of polyacrylamide.