In this paper, the pyrolysis process of mixed samples, bagasse with the addition of sludge, were investigated by TG-FTIR, and Py-GC/MS. For the mixed samples, the proportions of sludge were 10%, 30% and 50%. With the sludge ratio increased, the initial temperature and the terminated temperature increased. Eleven chemical structure groups were resolved from both of bagasse and sludge by KBr-Tabletting based FTIR analysis. Aromatic compounds, CO2, C=O, C-O, NH3 and HCN were the major gaseous products surveyed from the TG-FTIR inspection. The percentage of pyrolysis products (acetic acid, C7(#), furfural, benzene derivatives, C7(p)) were figured out from Py-GC/MS analysis. The addition of sludge was beneficial for the production of group C7p, whose carbon atoms exceeded 7. This research provided useful background knowledge for co-pyrolysis of bagasse and sewage sludge.