Powder metallurgy (P/M) Ni-based superalloy has been the most important material for high-temperature structural application in turbine disc owing to its good tensile and creep properties. However, the inclusions in P/M superalloy have an important impact on the safety and reliability of superalloy. By means of implanting Al2O3 and SiO2 inclusions artificially, the Low Cycle Fatigue (LCF) samples containing different sizes of inclusions were prepared. LCF tests with different strain amplitudes were carried out at 650 ℃. By observing and analyzing statistically the fracture of samples, the effect of size, location, types of inclusions and strain amplitude on the LCF lifetime were studied, the relationship between inclusion characteristics and LCF lifetime was constructed. The results showed that fatigue source areas were mainly internal inclusions or surface inclusions when the strain amplitude was 0.8% or 0.9%, and the inclusions greatly reduced the LCF lifetime. When the strain amplitude was 1.0% or 1.2%, the fatigue source areas had no inclusions, and the inclusions had no influence on LCF lifetime. Moreover, with the increase of strain amplitude, the locations of fatigue source were transferred from internal inclusions to surface inclusions and sample surface without inclusions gradually. With the increase of inclusions area, the LCF lifetime decreased at low strain amplitude, and the relationship between the inclusion area and the LCF lifetime was constructed. The effect of the distance from inclusions to the surface (L) on the LCF lifetime had no obvious rules when the inclusion area was uncertain. With the increase of L, the LCF lifetime increases linearly when the inclusion area was fixed. The effect of SiO2 inclusions on the LCF lifetime was more detrimental than Al2O3 inclusions when the inclusion area was within a certain range.