Abstract: In the indoor experiment，the seeds of Vallisneria natans were sown on the different substrates in order to study the sprout，morphology and biomass allocation in V. natans. The results showed that compared with the seeds of V. natans grown in thin layer of sponge and palm，the seeds grown in artificial silk cotton had more new leaves and bigger length of the longest root as well as total length of stem and leaf. However，some of V. natans grown in control group without substrate floated on water surface with wither leaves and they had lower growth parameters than other groups. In spite of the smallest number of roots，V. natans grown in control group had a higher biomass ratio of root to shoot and a larger number of plants with curved stem. The survival rate of V. natans grown in artificial silk cotton was bigger than other groups. And the survival rate of V. natans grown in artificial silk cotton，thin layer of sponge，palm and control group were 91%，88%，69% and 21% respectively. In conclusion，the growth and morphology of V. natans was greatly affected by different substrates. Without substrate，V. natans was likely to float on water surface and die；meanwhile，V. natans grown in the artificial silk cotton with loosen structure grew well. Considering the stability of root adhension and physical-chemical change of substrate submerged in water，the thin layer of sponge was the best substrate for V. natans in the indoor experiment.

Key words: substrate, Vallisneria natans, growth, morphology