A sanding disc stabilizing structure of an orbital sander, comprising: a casing, provided with a plurality of first installation holes; a sanding power source, assembled in the casing and the sanding power source comprising a drive shaft and a tool holder disposed on the drive shaft and offset from an axis of the drive shaft; a sanding disc, a center of the sanding disc disposed on the tool holder with a locking screw, the sanding disc comprising a base disc and a sanding pad disposed on the base disc, the base disc formed with a plurality of second installation holes on a side facing the casing, and the sanding disc driven by the sanding power source to perform an orbital motion relative to the casing; and at least four springs respectively comprising a first end disposed in one of the plurality of first installation holes on the casing and a second end disposed in one of the plurality of second installation holes on the sanding disc, wherein a free length of each of the at least four springs is greater than a spacing between an installation part of the casing provided for the first end and an installation part of the sanding disc provided for the second end, and each of the at least four springs is incompletely compressed in the spacing, during the orbital motion of the sanding disc, each of the at least four springs is stretched when the second end thereof deviates from a projection position of the first end; characterized in that: the plurality of first installation holes on the casing and/or the plurality of second installation holes on the sanding disc is provided with a plurality of rubber sleeves (112 or 135), and the first end and/or the second end of the at least four springs are respectively disposed in the plurality of rubber sleeves (112 or 135); wherein each of the plurality of rubber sleeves (112 or 135) comprises a cap (113 or 136) placed into the plurality of first installation holes or the plurality of second installation holes, and a flange (114 or 137) extending from a periphery of the cap (113 or 136) and disposed at an opening edge of the plurality of first installation holes or the plurality of second installation holes. a casing, provided with a plurality of first installation holes; a sanding power source, assembled in the casing and the sanding power source comprising a drive shaft and a tool holder disposed on the drive shaft and offset from an axis of the drive shaft; a sanding disc, a center of the sanding disc disposed on the tool holder with a locking screw, the sanding disc comprising a base disc and a sanding pad disposed on the base disc, the base disc formed with a plurality of second installation holes on a side facing the casing, and the sanding disc driven by the sanding power source to perform an orbital motion relative to the casing; and at least four springs respectively comprising a first end disposed in one of the plurality of first installation holes on the casing and a second end disposed in one of the plurality of second installation holes on the sanding disc, wherein a free length of each of the at least four springs is greater than a spacing between an installation part of the casing provided for the first end and an installation part of the sanding disc provided for the second end, and each of the at least four springs is incompletely compressed in the spacing, during the orbital motion of the sanding disc, each of the at least four springs is stretched when the second end thereof deviates from a projection position of the first end; characterized in that: the plurality of first installation holes on the casing and/or the plurality of second installation holes on the sanding disc is provided with a plurality of rubber sleeves (112 or 135), and the first end and/or the second end of the at least four springs are respectively disposed in the plurality of rubber sleeves (112 or 135); wherein each of the plurality of rubber sleeves (112 or 135) comprises a cap (113 or 136) placed into the plurality of first installation holes or the plurality of second installation holes, and a flange (114 or 137) extending from a periphery of the cap (113 or 136) and disposed at an opening edge of the plurality of first installation holes or the plurality of second installation holes. the plurality of first installation holes on the casing and/or the plurality of second installation holes on the sanding disc is provided with a plurality of rubber sleeves (112 or 135), and the first end and/or the second end of the at least four springs are respectively disposed in the plurality of rubber sleeves (112 or 135); wherein each of the plurality of rubber sleeves (112 or 135) comprises a cap (113 or 136) placed into the plurality of first installation holes or the plurality of second installation holes, and a flange (114 or 137) extending from a periphery of the cap (113 or 136) and disposed at an opening edge of the plurality of first installation holes or the plurality of second installation holes.