The invention discloses a method and a system for preparing red mud pellets. The method for preparing the red mud pellets comprises the following steps: drying red mud and calcium oxalate so as to obtain dried material and flue gas; performing wet-mixing treatment on the dried material with a reducing agent and a binder so as to obtain wet-mixed material; and carrying out pellet making treatment on the wet-mixed material so as to obtain the red mud pellets. The calcium oxalate is added into the red mud and then dried, the calcium oxalate is dried and heated to decompose to generate CO gas and CaCO3, wherein CO gas can destroy the stable pore passages in the red mud, so that the pore diameter is increased and the surface area is reduced; meanwhile, the capillary water in the red mud pores is reduced, and furthermore pelletizing is facilitated; moreover, the prepared pellet is large in porosity, and the pelletizing rate and the pelletizing efficiency are remarkably improved; CaCO3 obtained by decomposition of the calcium oxalate can be used as a reducing agent in a pellet reduction process, and the addition of the calcium-based reducing agent in the reduction process is omitted.