The present invention relates to bamboo manufacturing field, in particular, to a process for making a bamboo filament slab floor by opposite directional hot pressing. Aiming to overcome the defects that, while compressing, the existing bamboo filament slab floor at normal temperature under cold pressing is easy to rebound and expand, has low strength and weak resistance to abrasion and is easy to mildew while using for a long time, the present invention adopts shredding bamboo sheet, sizing treatment, molding bamboo filament and etc. procedures, characterized in that, a secondary drying procedure should be inserted between said sizing treatment and bamboo filament molding procedure; said sizing treatment should be implemented by soak sizing bamboo filament; said compressing includes opposite directional hot pressing of positive pressing and side pressing. The present invention adopts specific manufacturing technology, thus the floor can avoid the occurrence of holes and gaps inside bamboo filament slab floor and discharge formaldehyde and has stable quality, and will be not prone to mildew and deform while using for a long time. It can be widely used and suitable for indoor and outdoor flooring and various boards used in decoration and furniture.