The invention relates to a focal plane calibration method for an infrared lens of an astronautic camera. The focal plane calibration method comprises the following steps: an equivalent target is adopted to simulate a photosensitive plane of an infrared detector, a theodolite is used for observing an image of the equivalent target from the direction of an incidence port of the astronautic camera, the position of the equivalent target is adjusted, the target is located at the focal plane of the lens when the image of the equivalent target is clear, and the coarse calibration of the position of the focal plane is finished; and an interferometer is used for transmitting visible light plane waves, the visible light plane waves return from the surface of the equivalent target after being converged by the lens and are subjected to interference with incident light, the position of the equivalent target is finely adjusted, so that 2-3 interference fringes can exist, and the fine calibration for the position of the focal plane is finished. Under the condition that the infrared lens of the astronautic camera is a total-reflection type optical system, a focusing mechanism cannot be adopted, and the detector cannot work in a laboratory environment, the fast and high-precision calibration of the position of the focal plane of the lens can be finished by the focal plane calibration method.