Seeking high-performance computing methods to solve the problem of a large amount of calculation, low calculation efficiency, and small simulation scale on the traditional single central processing unit (CPU) platform is of great value to the simulation study of micro-structure. In this study, based on the three-dimensional multi-phase-field model of KKSO coupling phase-field and solute field, the open computing language (OpenCL)+ graphics processing unit (GPU) heterogeneous parallel computing technology is used to simulate the eutectoid growth of Fe-C alloy and the end growth process of pearlite under pure diffusion. The effects of initial supercooling and different diffusion coefficients on the growth morphology of lamellar pearlite were investigated. The results show that ferrite and cementite are perpendicular to the front of the solid-solid interface and are coupled and coordinated to grow, and there is no leading phase under the initial supercooling degree of 20 K. With the continuous increase of the initial supercooling degree (19 K-22 K), the morphology changes of the eutectoid layer are as follows: cementite stops growing → slice amplitude increases → regular symmetric growth→ oblique growth → layer merge. With the increase of the diffusion coefficient from 3×10-13 m2·s-1 to 15×10-13 m2·s-1, the growth rate of the microstructure of the lamellar pearlite increases linearly, and there is no obvious change in the frontal appearance of the pearlite.