The invention discloses a spacer selecting machine for a hanging plate spring seat. The spacer selecting machine comprises a rack (1), and is characterized in that an ejector cylinder (19), a lower pressing head (20), a vibration cylinder (24), a vibration bracket (22), a linear bearing (23), a guide shaft (17), a first linear bushing (16), a pushing disc (15) and a workbench (21) are arranged at the lower part of the rack (1); a control cabinet (4), a pressing cylinder (2), a transition connecting part (6), a guide shaft (3), a second linear bushing (5) and an upper pressing head (10) are arranged at the upper part of the rack (1); a pen type displacement sensor (8) on a bracket (25) of the transition connecting part (6) moves up and down along with a floating measuring head (9) on the upper pressing head (10) to generate a displacement signal; a PLC of the control cabinet (4) calculates to obtain an axial clearance of the bearings; and an electric signal sent out by the electric cabinet (4) controls operation of the cylinders. According to the spacer selecting machine, the stability of the clearance is guaranteed, the mounting efficiency of the plate spring seat and the product quality are improved, and the labor strength of operators is reduced.