The invention relates to the field of train interior and specifically relates to a sitting-lying dual-function bed. A turntable waist rest is arranged under back rests which are vertically arranged; a push-and-pull seat cushion is arranged on a lateral part of the turntable waist rest; a through shaft is arranged in the rear side of the push-and-pull seat cushion; the two ends of the through shaft are connected with L-shaped connecting blocks on the outer side of the push-and-pull seat cushion through slide blocks; the slide blocks are located in linear slide slots in the L-shaped connecting blocks; gears on the outer sides of the slide blocks on the through shaft are meshed with racks fixed on the outer sides of the L-shaped connecting blocks; fixing blocks are arranged on the L-shaped connecting blocks; curve slide slots are formed in the fixing blocks; the L-shaped connecting blocks under the fixing blocks are fixedly connected with supporting legs; an L-shaped supporting plate with a pin shaft is arranged at the bottom on the front side of the push-and-pull seat cushion; the L-shaped supporting plate can slide in the curve slide slots of the fixing blocks through the pin shaft; the waist rest is connected with air springs on the L-shaped connecting blocks through connecting shafts. The sitting-lying dual-function bed has the advantages of being simple in whole structure, flexible and varied, high in practicability, convenient in industrial production, and capable of being popularized and applied.