AlGaN/GaN high electron mobility transistors (HEMTs) have established terrific features in the high-power and high-frequency applications of microwave device. In this paper, the impact of silicon carbide polymorphs substrates including 6H-SiC, 3C-SiC and 4H-SiC on the performances of AlGaN/GaN double quantum well HEMTs (DQW-HEMTs) are analyzed and investigated. The results show that the devices with 4H-SiC and 6H-SiC substrates exhibit a higher transconductance of about 192 ms/mm at VDS = 15 V and a lower minimum noise figure (NFmin) of 0.48 and 0.42 dB at 10 GHz than those of devices with 3C-SiC, respectively. Whereas, DC-HEMT with 3C-SiC substrate has a transconductance of about 180 ms/mm at VDS = 15 V and a minimum noise figure of 3.01 dB at 10 GHz. On the other hands, the DC-HEMT with 3C-SiC substrate has lower drain gate capacitance (Cdg) and higher cut-off frequency (ft) than DC-HEMT with 4H-SiC and 6H-SiC substrates. The results demonstrate that AlGaN/GaN DH-HEMTs 4H-SiC and 6H-SiC substrates are promising devices for future high-power and high-frequency electron device applications.