  Primary {\gamma}' phase instead of carbides and borides plays an important
role in suppressing grain growth during solution at 1433K of FGH98 nickel-based
polycrystalline alloys. Results illustrate that as-fabricated FGH98 has
equiaxed grain structure and after heat treatment, grains remain equiaxed but
grow larger. In order to clarify the effects of the size and volume fraction of
the primary {\gamma}' phase on the grain growth during heat treatment, this
paper establish a 2D Cellular Automata (CA) model based on the thermal
activation and the lowest energy principle. The CA results are compared with
the experimental results and show a good fit with an error less than 10%. Grain
growth kinetics are depicted and simulations in real time for various sizes and
volume fractions of primary {\gamma}' particles work out well with the Zener
relation. The coefficient n value in Zener relation is theoretically calculated
and its minimum value is 0.23 when the radius of primary {\gamma}' is
2.8{\mu}m.
