Two-mode phase-field-crystal (PFC) method is used to simulate coherent boundary of nano-twins.It shows that atomic arrangement in coherent twin-grain boundary is not in good order as sphere grains grow and run into each other to form dislocations.Atomic arrangement in coherent twin-grain boundary as band-shape grains colliding each other is more tidy.For designing and controlling numbers of atomic layer in nano-twins,PFC model can be used to realize manipulation for coherent nano-twins structure.It is significant for guiding experiment and revealing nano-twins structure and properties.