The utility model discloses a transmission mechanism of a hand-operated potato harvester, which comprises a gearbox transmission mechanism, a lateral transmission mechanism and a shift wheel transmission mechanism. The transmission mechanism is characterized in that a seventeen-tooth bevel gear shaft in the gearbox transmission mechanism is connected with an outwardly extending spline shaft of a Gongnong-12K walking tractor, and the gearbox transmission mechanism is butted to a gearbox of the Gongnong-12K walking tractor through a butting pressure cover. A spline shaft in the gearbox transmission mechanism is connected to one end of an output shaft through a spline connecting sleeve, the other end of the output shaft is connected with a bevel gear in the lateral transmission mechanism, the bevel gear is connected with a bevel gear transmission shaft through a meshing bevel gear, the bevel gear transmission shaft is connected with a bevel gear in the shift wheel transmission mechanism, and the bevel gear in the shift wheel transmission mechanism is connected with a screen shift wheel through the meshing bevel gear and a screen drive shaft. The transmission mechanism of the hand-operated potato harvester is simple in structural design and convenient in assembly, and the technical problem that a hand-operated potato harvester in the prior art cannot be matched with the Gongnong-12K walking tractor is resolved.