Abstract: In the preceding article^[1], the relation between thermodynamics condition and inceptive cavitation stage has been discussed. In this paper, we try to introduce the volume function of inceptive cavitation bubbles, z₀(r), instead of the energy equation used in the reference ^[1],for discussing cavitation similarity problem in similar flow systems. Under this condition, theoretical result shows that the inception cavitation number K_i increases with a rise of geometry linear scale. In other words, if two flow systems are kept with similar pattern and liquid, it is impossible to satisfy the cavitation similarity. This conclusion accords with practice.