Abstract: Little is known about the comparative study of plant growth between plant floating-beds and constructed wetland wastewater treatment systems. Cyperus alternifolius floating-beds and constructed wetland domestic sewage treatment systems were established in plastic tanks (67cm51cm40cm) in South China Normal University. The seasonal changes of growth characteristics of C. alternifolius in plant floating beds and constructed wetland systems were similar. C. alternifolius maintained high growth rate from May to August, but had low growth rate from September to December. The tillers, number and porosity of first-class lateral roots of C. alternifolius in plant floating-beds were greater than those in constructed wetlands, but plant height, basal diameter, length and width of leaf, length and diameter of first-class lateral root of C. alternifolius in plant floating-beds were less than those in constructed wetlands. The biomass of C. alternifolius in plant floating-beds were greater than those in constructed wetlands in August, but lower in December.