The invention discloses a method and a device for determining a break-even period of a pumping unit well. The method comprises the steps of: acquiring a fluctuation range of a single-day oil production of a target pumping unit well within a preset time period; acquiring a fluctuation range of crude oil cost prices within the preset time period; comparing the fluctuation range of the single-day oilproduction with a first range threshold value; comparing the fluctuation range of the crude oil cost prices with a second range threshold value; determining a target period calculation formula according to comparison results; and determining the break-even period of the target pumping unit well based on the target period calculation formula. According to the method and the device disclosed by theinvention, the target period calculation formula is determined according to the fluctuation range of the single-day oil production of the target pumping unit well within the preset time period and the fluctuation range of crude oil cost prices within the preset time period, and the break-even period of the target pumping unit well is determined based on the target period calculation formula, thusthe break-even period can be determined without depending on the experience of technicians, thereby improving the precision of the break-even period.