The invention discloses a method and a device for simultaneously preparing bio-oil and white carbon black in a four-section manner of coupling, hydrolysis baking, pyrolysis and roasting. The method comprises the following steps: firstly, hydrolyzing a rice husk raw material with light bio-oil, removing most metal elements, and drying; further baking the dried rice husk, feeding into a spiral pyrolyzer for pyrolysis, feeding generated rice husk coke into a cross-flow moving bed roasting device for sufficient combustion so as to obtain a high-purity white carbon black product, performing gradient utilization on the high-temperature fume and heat generated after roasting as heat sources of pyrolysis, roasting and drying, and performing hydrolysis baking pretreatment, thereby improving the quality of the pyrolyzed bio-oil. Due to gradient utilization of the heat generated when the rice husk coke is roasted, the whole system needs no external heat supply; at the same time as the light bio-oil is taken as a hydrolysis solution for rice husk hydrolysis, the cost is reduced, and pollution is reduced; due to combination of light bio-oil hydrolysis and baking pre-treatment, the yield of pyrolyzed bio-oil can be increased, the quality of the pyrolyzed bio-oil can be improved, and the quality and the impurity of white carbon black can be also improved.