A slicing method of a toothbrush-shaped oil reservoir is applied to oil reservoir production. First, a construction preparation step comprises the steps of pulling out production strings; stabbing and washing oil tubes and sucker rods, and using a tubing gauge to penetrate the oil tubes one by one; dredging a well; scrapping casings; and flushing the well. A slicing string construction step comprises the steps of tripping in the slicing strings; and rotating a packer for setting. A slicing rod string construction step comprises the steps of tripping in slicing rod strings; and adjusting anti-impact stroke. In a well completion step, normal pumping of the oil well is achieved. The slicing method has the effects that the slicing method is applied to toothbrush-shaped oil reservoir oil wells, one time success rate of slicing is 100%, and single well yield of the oil wells is increased by an average of more than 2.5 tons.