The invention discloses a bidirectional-waterstop and vibration-damping elastic water seal device of a down-the-hole planar gate. The bidirectional-waterstop and vibration-damping elastic water seal device comprises structural steel, spring steel, a P-shaped water seal and waterstop rubber. The structural steel is fixedly arranged in a gate body. The spring steel is fixedly arranged on the inner side of the structural steel and fixedly connected with the structural steel through bolts. The waterstop rubber is arranged at one end of the structural steel. A backing plate is arranged on the outer side of the waterstop rubber and on one side of a gate groove. The P-shaped water seal is further arranged between the gate body and the gate groove. The bidirectional-waterstop and vibration-damping elastic water seal device of the down-the-hole planar gate is novel in structural design, and water leakage at the top of the gate can be effectively prevented and vertical vibration of the gate can be weakened in the waterstop and operating process of the down-the-hole planar gate.