The biomass for flammable gas production and its carbon deposition behaviour has been studied in a lab-scale fixed bed reactor, comprising pyrolysis and subsequent volatiles reforming produced in situ reaction. The distribution of pyrolysis products varies greatly with the addition of [email protected] Fe catalyst. During catalyst cycle process, both the char and heavy oil yield decreases significantly from 27.34% and 6.73% to 20.41% and 4.12%, respectively. This work also focuses on the carbon deposition of the [email protected] Fe catalyst used in the second step. The amount of coke on quartz tube wall (coke 1) decrease with increasing the temperature, and the surface carbon of the catalyst (coke 2) is found. Deactivated catalyst samples are recovered. The results present that the deactivation is attributed to the wrapping and covering of Fe by coke. There are reactions such as the coke deposition, the coke consumption, and the gasification reaction of char.