The invention relates to a multifunctional self-propelled shrub stubble flattening harvester, belonging to the forestry machinery field and mainly used for harvesting shrubwood. The multifunctional self-propelled shrub stubble flattening harvester mainly comprises a main engine and a cutting part, wherein the cutting part is respectively connected with two lifting arms and a turning arm of the host engine; the cutting part mainly comprises a saw disk, a gear box, a gear box seat, small belt wheels, a big belt wheel, a motor, a motor bearing block, a horizontal floating mechanism, a transversefloating mechanism, a fixing frame, a spring frame, a big tension spring, an induction rod, a coupler, a belt wheel shaft, a bearing with a block, and a protective cover. When the multifunctional self-propelled shrub stubble flattening harvester operates, the main engine transfers power to the motor, the motor drives the big belt wheel, the big belt wheel transfers the power to the two small beltwheels through belts, the small belt wheels transfer the power to the gear box, and the gear box drives the saw disk to rotate at high speed for cutting. If a place with geomorphic accidents exists in a cutting process, saws perform shape cutting with the terrain by left and right swinging of the transverse floating mechanism and up and down swinging of the horizontal floating mechanism.