The invention relates to a method for optimizing the timing of nitrogen injection oil extraction in a fracture-hole type oil reservoir, and relates to an oil and gas field exploitation technology; themethod comprises the following steps: (1) aiming at a target block, collecting original data of the oil reservoir and a real core; (2) recording the collected original data of the oil reservoir intoa data acquisition system, analyzing and determining the fracture-hole type of the target block; (3) loading the core into a high-temperature high-pressure fracture-hole type oil reservoir simulationdevice, simulating the fracture-hole type of the target block, simulating bottom water driving, setting the gas injection amount, the gas-liquid ratio, the gas injection speed and the bottom water energy, carrying out an oil extraction experiment under the set under the four conditions; (4) calculating the recovery rate and input-output ratio of the nitrogen injection oil compared to the bottomwater flood recovery oil, and the water input rate corresponding to the minimum input-output ratio, which is the best nitrogen injection timing for the target block. The optimal gas injection time ofthe method can ensure that the target block achieves the optimal economic benefit.