This study investigated the physiological and biochemical responses of two native grass species, Carex neurocarpa Maxim. and Carex siderosticta Hance, to drought and salt stress. Salt treatments were applied at five levels (0, 150, 250, 350, 500 mM) according to the soil chemical evaluation criteria (Ministry of Land, Infrastructure and Transport, 2019), while drought treatments were divided into five levels (no irrigation, biweekly, once a week, twice a week, and daily irrigation) based on landscape design soil standards and preliminary measurements of functional quantities. The experiment was conducted over one month from June to July, and photosynthetic rate, chlorophyll content, and biomass were measured before and after salt and drought treatments. Finally, malondialdehyde (MDA) levels and the K/Na ratio were analyzed. Carex neurocarpa Maxim. showed good growth under twice a week and daily irrigation, with the root/shoot ratio being highest with daily irrigation. Photosynthetic efficiency factors (Pn, gw, Tr, WUE) tended to be higher under daily and twice a week irrigation conditions, and could not be measured in the no irrigation treatment due to plants withering and dying. Moreover, low growth was observed in salt treatments exceeding 350 mM. Total growth tended to be highest in the untreated and 150 mM conditions. Photosynthetic efficiency factors gradually decreased with increasing salt concentration, and the K/Na ratio tended to be low in most treatments. Carex siderosticta Hance showed favorable growth in the biweekly to daily irrigation treatments under drought conditions. Total growth was highest with daily irrigation, and the photosynthetic rate tended to be highest in the twice a week condition. Furthermore, total chlorophyll content and chlorophyll a/b ratio were highest under daily irrigation conditions and tended to decrease gradually with decreasing irrigation frequency. Moreover, salinity treatment resulted in the highest growth in the no irrigation treatment and the lowest in the 500 mM condition. The total chlorophyll content was highest in the 150 mM condition and gradually decreased to the lowest in the 500 mM condition. Carex neurocarpa Maxim. appeared to exhibit weak resistance to both salt and drought stress, while Carex siderosticta Hance showed low resistance to salt stress but has some resistance to drought stress.