Fifty cultivated Catharanthus roseus seedlings were selected for tip-pruning treatment and the effects of tip-pruning on seedling growth and source-sink regulation were investigated for revealing physiological mechanisms of plants. The results showed that tip-pruning treatment resulted in obvious inhibition of apical dominance and enhancement of branching numbers. The contents of soluble sugars, acid sucrose invertase activity (AI) had a great change in differently positional leaves of the seedling. The sink strength in tip leaves of seedlings dramatically declined after tip-pruning treatment, while that in the leaves at the middle and bottom of seedlings had no obvious changes. The inhibition of apical dominance of tip leaves of seedlings was caused by the diminished sink strength due to tip-pruning treatment, Fifty cultivated Catharanthus roseus seedlings were selected for tip-pruning treatment and the effects of tip-pruning on seedling growth and source-sink regulation were investigated for revealing physiological mechanisms of plants. The results showed that tip-pruning treatment resulted in obvious inhibition of apical dominance and enhancement of branching numbers. The contents of soluble sugars, acid sucrose invertase activity (AI) had a great change in any positional leaves of the seedling. The sink strength in tip leaves of seedlings substantially declined after tip-pruning treatment, while that in the leaves at the middle and bottom of seedlings had no obvious changes. The inhibition of apical dominance of tip leaves of seedlings was caused by the diminished sink strength due to tip-pruning treatment,