Joule balance is a self-developed device for quantized reproducing the kilogram in China. It is particularly important to achieve mass value transfer based on the joule balance after the kilogram is redefined. However, there is a problem with the accuracy of joule balance measurements due to the exposure of standard weights to the air environment during the transfer of mass values. To address this problem, based on the structural characteristics of the joule balance, a combined weight transfer scheme is designed and proposed, and a corresponding weight vacuum transfer device is developed, which can transfer standard weights from the joule balance to the vacuum container in a vacuum environment, ensuring the accuracy of mass value transfer. Then, based on the joule balance suspension system, a transfer accuracy model of the transfer device is formulated. Based on this model, the weight transfer x is obtained. The transmission errors of the y-axis are 0.011 6 μm and 0.009 2 μm, respectively, demonstrating the accuracy of the weight transmission process. Finally, it is verified through experiments that the weight vacuum transfer device could introduce an alignment error of no more than 10-9 orders of magnitude to the joule balance, and does not affect the precision alignment state of the joule balance.