A comparative study of the quantitative characteristics of the rhizome of Phragmites australis populations in four habitats in the Zhalong Wetland was performed by sampling a unit volume of soil and measuring biomass and rhizome length. The results showed that P. australis returned green around May 10 and began to enter the vegetative growth period. There was a slow increasing trend in rhizome length from June to August, but a significantly increasing trend was observed from August to October. Moreover, rhizome length in the late period was 3.5-10.3 times higher than that in the early period. The middle and late growth seasons were the main periods of new rhizome supplement and growth of the population, during which time the spatial expansion of the population was achieved and more breeding buds were reserved for nutritional reproduction. Rhizome biomass and dry matter storage decreased gradually from June to August, but increased gradually from August to October, with the largest biomass observed in October, the end of the growth season, and was significantly higher than in other months(P < 0.05). The consumption of rhizome nutrients in the population mainly contributed to the germination of rhizome buds and the growth of young plants. The storage of rhizome nutrients also provided material support for the renewal and expansion of the population in the next year. The phenomenon of "super compensatory" storage in the rhizomes of the population was obvious. The length and biomass of rhizomes were the largest in the wet habitat, followed by the xeric, and aquatic habitats, however, they were the lowest in the saline-alkali habitat. The dry matter storage of rhizomes was the largest in the xeric habitat, followed by the wet and aquatic habitats, it was the lowest in the saline-alkali habitat. There was a significant, linear correlation between rhizome length of P. australis and the actual growth time after returning green. However, there was a significant, logarithmic correlation between rhizome biomass, dry matter storage, and the actual growth time after returning green, the goodness of fit of equation was 0.804-0.997, and the fitting equation reached a significant level of P < 0.01. The length, biomass, and dry matter storage of P. australis rhizomes in the four habitats showed relatively stable seasonal dynamics controlled by genetic factors during the growing period. The differences between the habitats and their differential orders were basically stable, showing significant environmental effects of soil factors, among which, the soil water content, organic matter, and available nitrogen were the positive drivers, while pH and available phosphorus were the negative drivers. The driving effects of soil water content and pH were the most prominent.