Abstract: Laser powder bed fusion (LPBF) has garnered significant attention due to its exceptional capability in fabricating complex structures, yet spattering during processing severely compromises the part qualities. In this study, synchrotron radiation X-ray ultrafast imaging is used to achieve in-situ observation of spattering behavior during LPBF of GH3536 alloy. Four typical spattering types are identified and validated in single-layer printing, which are metal powder spattering, metal jet spattering, powder and melted powder spattering, and coalesced powder spattering, while spatter re-melting and defect formation are observed during double-layer printing. The forming of spattering is regulated by the synergistic effect of back-flushing pressure of the molten pool surface and metal steam plume. The surface roughness of the part prepared increases with the increase of the scanning speed of laser, and with the decrease of the laser energy density. The spattering can be regulated by adjusting the LPBF process parameters. This study provides critical theoretical insights for optimizing LPBF parameters and suppressing spatter generation, and offers significant guidance for improving the quality of additive manufactured components.