The invention belongs to the field of the biological energy utilization, and provides a device and a method for preparing oil by co-catalytically pyrolyzing
forestry and agricultural wastes and
algae in a sectional manner. The method comprises the following steps: mixing
algae powder and
forestry and
agricultural waste powder to form a
raw material, soaking HZSM-5
powder in a precursor solution containing
gallium, and then soaking in a precursor
salt solution containing
nickel or
silicon to obtain a composite catalyst; enabling carrier gas to enter from top of a heating section I; conveying the
raw material to the heating section I by virtue of a spiral conveyor, enabling a non-condensed gas to rise to a projection section of the heating section I, placing the catalyst on a catalyst
cushion layer of the projection section, after the
pyrolysis is finished, turning an insert plate for 180 degrees, enabling the low-temperature product to fall into a heating section II, and enabling the carrier gas to enter from the bottom of the heating section II. A projection section at an outlet of the heating section II is provided with a
cushion layer of self-made composite catalyst. The reaction residual
coke is collected into a collection tank by virtue of an overturning stainless steel carrier net, and volatile components are collected into a liquid collector after being condensed. The low-
oxygen high-quality biological oil is generated by utilizing the process, so that the conversion efficiency can be increased, and the
carbon deposit deactivation of a
molecular sieve can be effectively reduced.