To improve the imaging quality of optical lenses and eliminate the influence of stray light， an antireflective film with an average reflectance of less than 0.1% in the visible wavelength range was designed on a K9 glass substrate. Using electron beam evaporation as the preparation method， to address the issues of high sensitivity and large spectral changes in thin films， a mathematical model was established to stabilize the control of film thickness， reduce film thickness errors， improve preparation accuracy， and film formation stability. Environmental testing experiments were conducted on the antireflective film， in which the process parameters were continuously optimized and adjusted， with a focus on improving the hardness and water boiling resistance of the antireflective film. The experimental results show that the average reflectance of the prepared antireflective film is approximately 0.044% and the highest reflectance is 0.071 2% in the band range of 420-680 nm. Thus， problems caused by the poor mechanical properties and chemical stability of the antireflective film with MgF₂ as the outer layer are overcome. Further， the developed film meets the requirements of low loss， stability， reliability， high strength， and repeatable preparation in engineering applications.