An air spring for rail transit, comprising: an upper plate fixedly connectable to a car body; and an air bag hermetically fixedly connected to the upper plate ; and further comprising: an hourglass shaped spring assembly hermetically connected to the air bag , wherein the hourglass shaped spring assembly comprises an hourglass shaped spring and a position-limiting component arranged inside the hourglass shaped spring , the shape of the hourglass shaped spring is a smooth camber, which has a small upper end, and extends downwards gradually to a largest portion, and then is further gradually diminished towards a bottom end, and the position-limiting component comprises a hard boss extending downwards; and the hard boss has a height less than a height of the hourglass shaped spring , a height difference between the hard boss and the hourglass shaped spring is a stop gap of the hourglass shaped spring assembly , a gap between the upper plate and the hourglass shaped spring assembly is a space gap, and the sum of the space gap and the stop gap of the hourglass shaped spring assembly can be configured to be equal to a maximum sinking amount that the car body is allowed. an upper plate fixedly connectable to a car body; and an air bag hermetically fixedly connected to the upper plate ; and further comprising: an hourglass shaped spring assembly hermetically connected to the air bag , wherein the hourglass shaped spring assembly comprises an hourglass shaped spring and a position-limiting component arranged inside the hourglass shaped spring , the shape of the hourglass shaped spring is a smooth camber, which has a small upper end, and extends downwards gradually to a largest portion, and then is further gradually diminished towards a bottom end, and the position-limiting component comprises a hard boss extending downwards; and the hard boss has a height less than a height of the hourglass shaped spring , a height difference between the hard boss and the hourglass shaped spring is a stop gap of the hourglass shaped spring assembly , a gap between the upper plate and the hourglass shaped spring assembly is a space gap, and the sum of the space gap and the stop gap of the hourglass shaped spring assembly can be configured to be equal to a maximum sinking amount that the car body is allowed. an hourglass shaped spring assembly hermetically connected to the air bag , wherein the hourglass shaped spring assembly comprises an hourglass shaped spring and a position-limiting component arranged inside the hourglass shaped spring , the shape of the hourglass shaped spring is a smooth camber, which has a small upper end, and extends downwards gradually to a largest portion, and then is further gradually diminished towards a bottom end, and the position-limiting component comprises a hard boss extending downwards; and the hard boss has a height less than a height of the hourglass shaped spring , a height difference between the hard boss and the hourglass shaped spring is a stop gap of the hourglass shaped spring assembly , a gap between the upper plate and the hourglass shaped spring assembly is a space gap, and the sum of the space gap and the stop gap of the hourglass shaped spring assembly can be configured to be equal to a maximum sinking amount that the car body is allowed. <EOS>