Seven-speed automatic transmission for vehicle

The invention discloses a seven-speed automatic transmission for a vehicle. The seven-speed automatic transmission comprises a hydraulic torque converter used for providing power, a planetary mechanism, a hydraulic retarder and an operation mechanism positioned between the hydraulic torque converter and the planetary mechanism, wherein the planetary mechanism comprises four rows of independent planetary gear sets; each row of planetary gear set comprises a gear ring, a planet carrier, a planetary gear and a solar wheel; the operation mechanism comprises three clutches and four brakes; the clutches and the brakes are controlled to close, so that speed ratio choices of different gears are realized, and seven-gear transmission and reverse gear are formed. The seven-speed automatic transmission not only can improve dynamic property, fuel oil economical efficiency and exhaustion performance of the vehicle, but also can meet needs of people for multi-road-condition multi-gear driving pleasure, also can enable the engine output power to be connected smoothly and can enable gear shifting to be more comfortable, and has the advantages of a reasonable design and compact layout.