The invention discloses a low-loss power synthesis network of a power amplifier, comprising: a power synthesis module, a power supply filter module, an impedance matching module and a stability module. The power synthesis network has the advantages of compact structure, simple design method, large power capacity, low insertion loss and higher harmonics suppression effect, and can be powered on twosides or on a single side according to the actual use conditions, which simplifies a peripheral circuit; the novel low-loss power amplifier power synthesis network can be widely applied to the designof a planar high power amplifier.