We conducted a glasshouse experiment as a  factorial in randomized study with six replications on pasture species of Schoenoplectus triqueter in Gonbad Kavoos University from 2012-2013. Treatments included height waterlogging in four levels (control, equal to the water surface, 10 cm below the water surface, 20 cm below the water surface) and waterlogging period over three levels (10, 20 and 30 days). In this investigation, we measured the morphological traits (length root, the number of rhizome, length rhizome, the number of internode, dry weight of root, dry weight of rhizome, the number of shoot stems and shoot dry weight) and physiological traits (proline and chlorophyll content). The results showed that the contraction effect of period × height waterlogging was significant in 1% level on all studied traits expect for root volume.  We observed increased length and dry weight of root, the number of rhizome, length rhizome, number of internode, and number of shoot stems at a treatment of 10 cm below the water surface in three periods of waterlogging and with an increase of waterlogging period. The highest proline and chlorophyll contents were observed in the control group and the group with 10 cm below the water surface. This species could be introduced to flood resistance.