In Sassanid kingdom, several great and small families inhabited all over Iran, among which seven families of Kāran, Suren, Spāhbad, Mehrān, and Spandiaz, Zik and the house of Sassanid were more noble and powerful than others. The members of these seven families were known as the noblest Iranians and the heads of these families were very powerful in the Sassanid court. The connection of these families with the king was a combination of conflict and cooperation; in the time of authority of Sassanid kingdom, Iranian grandees and the heads of great families were obedient to the king, but when the king was weak, the true rulers of Iran were grandees and the heads of great families. Nevertheless, during the Sassanid history, Iranians believed that the king of Iran should be a member of Sassanid lineage; therefore other Iranian families, despite all their power and the occasional weakness of Sassanid kingdom and civil wars and chaos, did not ignore this belief and did not demand the kingdom at least until the last decades of Sassanid kingdom. The main question of this research is “How was the connection of the members of great families or Iranian seven families and grandees with the king from the rise of Sassanid to the reign of Ghobad I (488-531A.D)?” This paper reveals that the connection of Iranian grandees and families with the king was a combination of conflict and cooperation; in the time of powerful and warrior kings, great Iranian families were obedient to the king and when the king was weak, the true rulers of Iran were nobles and the heads of great families.