The invention relates to an automatic elasticity balancing device of a hanger. The automatic elasticity balancing device is characterized in that an upper-end connecting lug (1) is arranged at the upper end of a hanger housing (10), a base sleeve (11) is arranged at the lower end of the housing (10), a guide limit shaft (9) is arranged on the base sleeve (11) in the housing (10), the upper end of the guide limit shaft (9) is fixed on the upper-end connecting lug (1) by a guide limit shaft nut (2), a limiting stand (7) is arranged on the guide limit shaft (9), a telescopic driving shaft (8) is sheathed in the housing (10) through the base sleeve (11) in a penetrating manner, a middle sliding plate (5) is arranged at the upper end of the telescopic driving shaft (8) and used for limiting, the middle sliding plate (5) is sheathed on the guide limit shaft (9) and can slide up and down along with the guide limit shaft (9), a spring (6) is sheathed on the telescopic driving shaft (8) in the housing (10) between the middle sliding plate (5) and the base sleeve (11), a lower connecting head (12) is fixed on the lower end of the telescopic driving shaft (8), and an arch-shaped balance connecting plate (14) is fixed on the lower connecting head (12) through a bolt (13). With the adoption of the automatic elasticity balancing device of the hanger, a locomotive can be ensured to safely, smoothly and successfully pass at high speed.