The invention provides an optical fiber loose tube production device. The optical fiber loose tube production device is characterized in that a pre-positioned tension control mechanism is arranged in a warm water cooling water tank; the pre-positioned tension control mechanism is used for dividing the warm water cooling water tank into two warm water sections; a warm water cooling water tank part between the pre-positioned tension control mechanism and an extruding machine head is the first warm water section; and a warm water cooling water tank part between the pre-positioned tension control mechanism and a cold water cooling water tank is the second warm water section. A working principle of the optical fiber loose tube production device is as follows: a warm water cooling water section is divided into the first warm water section and the second warm water section; the first warm water section and the second warm water section are sequentially arranged along the conveying direction of optical fibers; the crystallization condition of materials of a loose tube in the first warm water section is the same as that of prior art, namely the loose tube has a certain anti-pressure capability by crystallization under a forced tension state, so that the optical fiber loose tube is convenient to draw; and in the second warm water section, the tension of the loose tube is controlled to zero or be close to zero, so that the loose tube is annealed and is continually crystallized under loose and free states, and the after-contraction problem of the loose tube is solved.