The invention discloses an oil and gas pipeline non-stop transmission on-line desanding device and aims to overcome the defects that in the prior art, installation is complicated, and the separation effect is poor. The desanding device comprises a desanding device inlet, a desanding device outlet, a desanding device cylinder, a columnar cylinder, a helical blade, rotation-stopping fan-shaped plates, sand discharging outlets and full-bore ball valves, wherein the columnar cylinder is in the desanding device cylinder, the columnar cylinder is coaxial to the desanding device cylinder body, the helical blade is located in an annular space between the desanding device cylinder and the columnar cylinder to form a helical flow channel, the rotation-stopping fan-shaped plates are in the desandingdevice cylinder, the sand discharging outlets are formed in the lower side of the desanding device cylinder in a row, and the sand discharging outlets run through the full-bore ball valves and sand inlets in sequence to be communicated with a sand storage chamber. By means of the oil and gas pipeline non-stop transmission on-line desanding device, the installation way of the desanding device is identical to that of a common valve, the desanding device can be horizontally or vertically installed and occupies little space, auxiliary facilities are not needed, the separation efficiency is high, solid impurities in oil and gas can be efficiently separated out, and normal pipeline transportation is not affected in the sand cleaning process.