Drought stress is one of major limiting factors for switchgrass in many areas. This study was to assess drought tolerance of 10 upland and lowland switchgrass varieties.  The grass was grown in pots and under well-watered or drought stress conditions for 30 days in a greenhouse.  CO2 fixation rate, stomatal conductance, water use efficiency, leaf relative water content, cell membrane stability, and various metabolites in leaf tissues were measured. The results showed that there were significant differences in drought tolerance between varieties. Overall, BN-13645-64 and TEM-SEC had greater cell membrane stability (lower electrolyte leakage), higher CO2 fixation rate, water use efficiency and leaf relative water content, and less leaf wilting relative to BN-12323-69 and BN-18757-67 under drought stress, indicating BN-13645-64 and TEM-SEC had greater drought tolerance than BN-12323-69 and BN-18757-67. A total of 43 switchgrass varieties has been screened for drought tolerance.