A foldable knife comprises a blade, a first rotary knife handle, a second rotary knife handle and a locking device. The tail end of the blade is provided with a front fixing column and a rear fixing column. The first rotary knife handle and the second rotary knife handle respectively comprise a first knife handle plate and a second knife handle plate. The front end of each first knife handle plate and the front end of each second knife handle plate are located on the two sides of the tail end of the blade respectively, and the first knife handle plate and the second knife handle plate are hinged through a hinge pin. Each first knife handle plate and the corresponding second knife handle plate are fixed in parallel through limiting pins located at the rear end of the first knife handle plate and the rear end of the second knife handle plate. According to the foldable knife, the tail end of the blade is provided with the front fixing column and the rear fixing column, the first rotary knife handle and the second rotary knife handle are symmetrically arranged on the two sides of the front fixing column and the rear fixing column, the first rotary knife handle and the second rotary knife handle are locked through the locking device when folded or unfolded, forces borne by the blade in all directions are balanced, the blade is stable, and therefore the foldable knife is safe in use.