The Scanning Electron Microscope (SEM) with energy dispersive spectrometer (EDS) and Electron Back-Scatter Diffractometer (EBSD), Optical Microscope (OM) and the thermal simulation testing machine were used to study the effect of the powder size distribution on the hot deformation behavior and the organizational differences of a novel nickel-based powder metallurgy superalloy (WZ-A3). The results show that: compared with powder preparation of HIP-01, the dendrite structure of coarse powder is obvious and the composition segregation is serious. The residual primary γ′ of the HIP-02 made by the coarse samples is more than the HIP-01. At the low temperature (1050℃, 1080℃) and high strain rates (1/s, 0.1/s), the peak stress of HIP-01 is higher than that of HIP-02. After hot compression, the crack situation at the edge of HIP-01 is more serious than that of HIP-02. Most of the original HIP-01 microstructure are retained, and the crack is generated at the Prior Particle Boundary (PPB), while some recrystallized structure appears at the edge of HIP-02. At 1080℃-0.001/s, the peak stress of HIP-02 sample is about 30MPa lower than that of HIP-01. The recrystallization phenomenon of HIP-02 during hot compression is obvious. The recrystallized grains of the HIP-02 are uniform. The HIP-01 has necklace crystal structure, and the recrystallization is not sufficient. The coarse γ" can promote the recrystallization of HIP-02 sample at 1050℃ and 1080℃. At high temperature (1150℃) and low strain rates (0.001/s, 0.01/s), the γ" dissolve into γ matrix, and the thermal deformation behavior of the two samples is similar. No cracks occur in the samples, and the microstructure is fully recrystallized. The abnormal grown grains were found in 1150℃-0.001/s at the both two samples.