Distribution patterns of four seedling populations of the mangrove Avicennia marina in Southern-China Coast were analyzed using the multifractal method of fractal theory. The results showed that the patterns exhibited multi-scaling and multifractal behavior varying with the scales of observation. With q values changing from −2 to 4, values of Dq ranged from 1.078 to 1.997, ƒ(α) from 0.402 to 1.678, and α(q) from 0.909 to 2.480. The values of multifractal parameters were closely related to aggregation intensity of populations. The differences (D0 – D1) and [ƒ(-1)-D0] were an effective index for measuring the degree of spatial heterogeneity of patterns. Hydrodynamic regimes, bare soils of different areas, the bafflement of plant canopy, etc. might be the major factors controlling the formation of multifractal patterns of A. marina seedling populations.