The invention relates to a 3D printing wire mixing mechanism. The 3D printing wire mixing mechanism comprises a storage box, conveying pipes, a motor, a transmission wheel A, a scraper, bearings, a transmission wheel B, a transmission belt, a discharging pipe, a heating layer, a thermal insulation layer and a temperature sensor; the storage box is provided with the multiple conveying pipes which are linearly arranged; a motor is arranged on the storage box and located on one sides of the conveying pipes; the transmission wheel A is arranged on a rotary shaft of the motor; the scraper is horizontally arranged in the storage box and located on the lower sides of the conveying pipes, and the two ends of the scraper are connected with the storage box through the bearings; the transmission wheel B is arranged on the same sides of the scraper and the transmission wheel A, the transmission wheel A is in transmission with the transmission wheel B through the transmission belt; and the bottom of the storage box communicates with the discharging pipe, the outer side of the discharging pipe is provided with the heating layer, the outer side of the heating layer is provided with the thermal insulation layer, and the discharging pipe is provided with the temperature sensor. The 3D printing wire mixing mechanism has the beneficial effects that the structure is simple, the working efficiencyis high, and the problem that wires with multiple colors are difficult to mix uniformly when being used at the same time is well solved.