Abstract: In order to investigate the influence of vertical vacuum dyeing method on the green wood of Populus cathayana, reactive red X-3B was adopted to dye the green wood of P. cathayana by the design of single factor experiment in this study. The results showed that the dyeing area increased gradually with the rise of vacuum degree and dye concentration. The dyeing area experienced an increase first and then decreased along with the rise of vacuum time. With the rise of dyeing time, the dyeing area increased quickly, then decreased gradually and reached balance. Under the same dyeing process and same wood, with the rise of wood height, the dyeing area generally decreased first and then increased.