A system for imaging in air, comprising: an image source, a retroreflective element and a transflective mirror, light emitted by the image source is irradiated on the retroreflective element after being reflected by the transflective mirror, the light is reflected by the retroreflective element and emerges in an opposite direction along an original incident path, and then forms a real image after being transmitted by the transflective mirror; wherein a selective transmissive film is provided on a side of the transflective mirror facing the image source, the selective transmissive film is configured to have a reflectance to first linearly polarized light greater than a reflectance to second linearly polarized light, and a transmittance to the second linearly polarized light greater than a transmittance to the first linearly polarized light, a polarization direction of the first linearly polarized light is perpendicular to a polarization direction of the second linearly polarized light; and a phase delay optical element is provided on a side of the retroreflective element facing the transflective mirror such that the first linearly polarized light of the image source incident on the retroreflective element from the transflective mirror becomes circularly polarized light after passing through the phase delay optical element, the image source comprises a polarized light source, the polarized light source is an s-polarized light source, the first linearly polarized light is s-polarized light, the second linearly polarized light is p-polarized light, and the s-polarized light source is located on a side of the transflective mirror facing the retroreflective element; characterizes in that a component of the selective transmissive film comprises one of a metal oxide, a metal nitride, a metal oxynitride coating film and an organic polymer; or the selective transmissive film comprises one or more film layers, and a component of each film layer comprises one of a metal oxide, a metal nitride, a metal oxynitride coating film, and an organic polymer; and in that the light emitted by the image source is selected to be s-polarized light of a specific wavelength band, and the selective transmissive film is configured to have a reflectance of greater than 70% for the s-polarized light of the specific wavelength band, and a transmittance of greater than 70% for s-polarized light of other wavelength bands and the p-polarized light within a visible light band, the specific wavelength band comprises red light of 590 nm to 690 nm, green light of 500 nm to 565 nm, and blue light of 410 nm to 480 nm. light emitted by the image source is irradiated on the retroreflective element after being reflected by the transflective mirror, the light is reflected by the retroreflective element and emerges in an opposite direction along an original incident path, and then forms a real image after being transmitted by the transflective mirror; wherein a selective transmissive film is provided on a side of the transflective mirror facing the image source, the selective transmissive film is configured to have a reflectance to first linearly polarized light greater than a reflectance to second linearly polarized light, and a transmittance to the second linearly polarized light greater than a transmittance to the first linearly polarized light, a polarization direction of the first linearly polarized light is perpendicular to a polarization direction of the second linearly polarized light; and a phase delay optical element is provided on a side of the retroreflective element facing the transflective mirror such that the first linearly polarized light of the image source incident on the retroreflective element from the transflective mirror becomes circularly polarized light after passing through the phase delay optical element, the image source comprises a polarized light source, the polarized light source is an s-polarized light source, the first linearly polarized light is s-polarized light, the second linearly polarized light is p-polarized light, and the s-polarized light source is located on a side of the transflective mirror facing the retroreflective element; characterizes in that a component of the selective transmissive film comprises one of a metal oxide, a metal nitride, a metal oxynitride coating film and an organic polymer; or the selective transmissive film comprises one or more film layers, and a component of each film layer comprises one of a metal oxide, a metal nitride, a metal oxynitride coating film, and an organic polymer; and in that the light emitted by the image source is selected to be s-polarized light of a specific wavelength band, and the selective transmissive film is configured to have a reflectance of greater than 70% for the s-polarized light of the specific wavelength band, and a transmittance of greater than 70% for s-polarized light of other wavelength bands and the p-polarized light within a visible light band, the specific wavelength band comprises red light of 590 nm to 690 nm, green light of 500 nm to 565 nm, and blue light of 410 nm to 480 nm.