The invention discloses an automobile and a speed changer thereof. The speed changer comprises a shell, an input shaft, a Ravigneaux planet gear mechanism, and first and second single-row and single-stage planet gear mechanisms, wherein the first single-row and single-stage planet gear mechanism comprise a first sun gear, a first planet gear, a first planet carrier and a first inner gear which are sleeved on the input shaft; the Ravigneaux planet gear mechanism comprises a larger sun gear, a smaller sun gear, a longer planet gear, a shorter planet gear, a planet carrier and an inner gear ring; the larger and smaller sun gears, the first inner gear ring, the planet carrier are connected separably with the input shaft; the second single-row and single-stage planet gear mechanism comprises a second sun gear, a second planet gear, a second planet carrier, a second inner gear ring, a first brake, a second brake and a third brake; the second inner gear ring is connected with the input shaft; the second planet carrier is fixed on the planet carrier; the first brake is used for braking the larger sun gear; the second brake is used for braking the planet carrier; and the third brake is used for braking the second sung gear. According to the speed changer, seven forward gears are designed; and the speed changer is simple in structure, and has high shifting efficiency.