Disclosed are an undercarriage (100) and an aircraft using the undercarriage (100). The undercarriage (100) comprises two supporting legs (70) which are oppositely arranged, a fixing mechanism (10) on which the two supporting legs (70) are pivoted, a driving mechanism (30) arranged on the fixing mechanism (10), and a translation part (51) which is connected to the driving mechanism (30) and can be driven by the driving mechanism (30) to move relative to the fixing mechanism (10); the two supporting legs (70) are glidingly connected to two ends of the translation part (51); and the driving mechanism (30) drives the two supporting legs (70) to rotate relative to the fixing mechanism (10) through the translation part (51). The undercarriage (100) and the aircraft using the undercarriage (100) are light in overall weight and relatively low in manufacturing cost.