The utility model discloses a multi-rotor unmanned aerial vehicle arm structure fast to disassemble and assemble, which comprises a vehicle arm seat assembly and a vehicle arm sleeve assembly, the vehicle arm seat assembly comprises an adjusting sleeve, a vehicle arm seat sleeve, a vehicle arm seat plug positioning seat, a vehicle arm seat motor plug, an undercarriage plug, a vehicle arm seat plugpositioning sheet and a vehicle arm seat locking screw; the head end of the vehicle arm seat sleeve is sleeved with the adjusting sleeve, a positioning pin is arranged on the inner wall of the adjusting sleeve, and a sliding groove in sliding fit with the guide groove and a limiting groove communicating with the sliding groove are formed in the outer wall of the vehicle arm seat sleeve; a plurality of steel ball holes with steel balls are formed in the side wall of the engine arm seat sleeve; the vehicle arm sleeve assembly comprises a vehicle arm pipe sleeve, a vehicle arm sleeve plug positioning piece, a vehicle arm sleeve motor plug, an undercarriage, a vehicle arm sleeve plug positioning base and a vehicle arm sleeve locking screw. An annular groove connected with the steel ball in aclamped mode is formed in the outer wall of the vehicle arm pipe sleeve. The unmanned aerial vehicle arm structure of the structure is rapid to disassemble and assemble, stable in installation, convenient to maintain and high in product interchangeability.