The invention provides a gas-liquid-
solid separation device in a shaft. The upper end of an outer
pipe is connected to an upper connector through matching with an outer buckle, and a plurality of liquid inlet holes penetrating through the outer
pipe are formed in the upper end of the outer
pipe; an inner pipe is inserted into the outer pipe and is spaced from the outer pipe, and the upper end of the inner pipe is connected to the upper connector through matching with an inner buckle; a
diameter expanding short section is connected to the lower end of the inner pipe so as to be suspended in theouter pipe; the inner pipe, the
diameter expanding short section and the outer pipe jointly define an inner pipe annular space and an outer pipe annular space, and the inner pipe annular space and the outer pipe annular space meet the preset flow area; the flow area of the
diameter expanding short section is not smaller than the flow area of an externally-connected upper pump oil pipe; a lower connector is connected to the lower end of the outer pipe through a
screw thread; and the lower end of a lifting short section is connected to the upper end of the upper connector in an inserted mode, and an oil pipe section hoop is connected to the upper end of the lifting short section in a sleeving mode. The invention further provides a design method of the gas-liquid-
solid separation device in the shaft. Compared with the prior art, the gas-liquid-
solid separation device in the shaft is good in reliability and long in service life.