The invention relates to a coal supporting plate supporting device for a tamping coke oven coal car, which relates to a tamping coke oven device. In the prior art, because the coal supporting plate can generate downwarping in delivering coals to cause damage to the bottom of the coal supporting plate, the service life of the coal supporting plate is short. For the coal supporting plate supporting device, a supporting roller assembly is arranged on the front part of a coal supporting plate slideway on the coal car body, wherein the supporting roller assembly consists of a supporting roller, a supporting roller shaft, a rolling bearing and a supporting roller support; the rolling bearing is arranged between the supporting roller and the supporting roller shaft; the supporting roller shaft is supported on the supporting roller support; and the supporting roller support is connected to the car body through bolts and is welded with the car body through a stop dog. Because the supporting roller assembly is arranged on the coal supporting plate supporting device, the coal supporting plate is supported and the stress state of the coal supporting plate is improved, the friction resistance in delivering the coals can be reduced effectively, the stress concentration on the coal supporting plate and a slideway lining plate, and the service lives of the coal supporting plate and the slideway lining plate is prolonged.