The invention relates to a belt type lower guide rail device. The belt type lower guide rail device comprises a guide rail and a covering piece, wherein the guide rail is provided with two parallel grooves, the covering piece covers in the guide rail and is tightly adhered to the guide rail, the covering piece is connected with a sliding block of a door leaf, the length of the covering piece is twice as long as the width of the door leaf, the top part of the covering piece is flush with the upper edge of the grooves, the covering piece is arranged in a door closing direction of the door leaf, the lower part of the covering piece is provided with an antifriction sliding block or an antifriction roller, and the covering piece is made from metal material or non-metal material. Compared with the prior art, according to the belt type lower guide rail device disclosed by the invention, the grooves on the guide rail are completely covered into a complete plane when a door is opened, and thus a passenger cannot be knocked down due to the high-low difference existing in the guide rail; meanwhile, the grooves are covered by the covering piece, and thus the normal closing of the door leaf cannot be affected as some small objects can not fall into the guide rail; and since the grooves are covered, the chances that the edges of the grooves are knocked against can be reduced, the abrasion degree of the edges of the grooves can be greatly lowered, and the service life of the guide rail is prolonged.