We report ultrafast charge migration in ionized iodo-alkyne chain I(CC) nH+ for n = 1, 2, …, 5. The dynamics of electron density become more complicated with the increasing length of the molecular chain. However, the essential properties of charge migration in I(CC) nH+ can be clearly interpreted in terms of the electron flux. By systematic investigations of the dynamics of electron density, hole density, and the electron flux for different molecules, the size dependence of charge migration in I(CC) nH+ is discussed.