Stretchable passenger car seat backrest

The invention discloses a stretchable passenger car seat backrest, which comprises a backrest, a main airbag arranged in the backrest, and a framework comprising a backrest framework and a side framework. The stretchable passenger car seat backrest is characterized by further comprising two secondary airbags symmetrically arranged on two sides of the main airbag, wherein the main airbag is arranged in a backrest core in front of the backrest framework; the secondary airbags are positioned at the inner sides of the side framework; an air inlet passage and an air outlet passage communicated with each other are arranged between the main airbag and the secondary airbags; the secondary airbags are provided with expandable side safety airbags which are positioned on the outer sides of the side framework; the main airbag is provided with a main air inlet and a main air outlet; the secondary airbags are provided with secondary air inlets and secondary air outlets; and the main air inlet is connected with the secondary air inlet through an air valve and a power source respectively. The stretchable passenger car seat backrest not only can increase the driving interest of a driver, but also can effectively protect the driver and reduce side impact injuries when the passenger car undergoes front and side impacts.