The invention discloses a safe-to-use heater for a diesel oil filter. The safe-to-use heater comprises a ring block, wherein the lower surface of a fixed disc is welded at top of the ring block; a first through hole is formed in the middle of the fixed disc; a fixed cover is arranged at top of the fixed disc; a second through hole is formed in the middle of the fixed cover; the lower surface of the fixed cover is fixedly connected with top of a fixed ring; outer surface of the fixed ring is in threaded connection with the inner surface of the first through hole; and a third through hole is further formed in the fixed disc and is formed in one side of the first through hole. According to the safe-to-use heater for the diesel oil filter, the fixed disc is welded at top of the ring block, the first through hole is formed in the middle of the fixed disc, the diesel oil filter can be inserted in the ring block, a heating component is not in direct contact with diesel oil, the heater is connected onto the diesel oil filter in a sleeving manner, heating in water bath is adopted to enable heating to be more uniform and safer, and the safe-to-use effect is realized.