Gas quenching granulation is one of the most important modern methods utilized in molten steel slag (MSS) treatment, more positive and accurate simulated methods play a crucial role in guiding the whole gas quenching which dominate the stability, cementitious activity, magnetic separation of Magnetite and sensible heat recovery of MSS products, etc. However, the frequently used Volume of Fluid (VOF) methods can only predict the fragmentation process, but there appeared much deviation in identifying and calculating subsequent particle fragmentation and particle size distribution changes. To address these noticeable deviations, the VOF to DPM model is innovatively introduced to clarify the morphological spatial and temporal evolution for MSS by designing a transition from the continuous phase to the discrete phase for the divergent liquids. The DPM model is expert in tracking MSS particles in DPM form, and the motion, size changes, particle concentration and size distribution of divergent liquids were real-time counted and measured. Compared to the on-site particle size obtained using the air-quenching at Zhengfeng Steel Plant in China, the relative error between the two was less than 10%. The morphological spatial and temporal evolutions of MSS in the main body region, non-mutual adhesion region and particle field region were systematically studied from qualitative and quantitative aspects under different working conditions. Finally, scientific data was provided to optimize process parameters and improve granulation efficiency. These research findings provide valuable universal applicability in all the fields of gas quenching and fragmentation process and lay a theoretical foundation for subsequent strictly controlled granulated particles.