The invention discloses an armored car window fastening structure with explosion preventing and buffering functions and a fastening method thereof. The armored car window fastening structure comprises an installation frame body and a transparent window fixed to an armored car body through the installation frame body. A circle of prestressed structure frame body is arranged on the side edge of the transparent part in a combined mode, and fastening structure bodies which are matched are formed between the prestressed structure frame body and the installation frame body. A rigid frame body of a prestressed structure is arranged on the periphery of the transparent window in a combined mode, the transparent window is installed in cooperation with the armored car installation frame body through the rigid frame body, so that the window is prevented from integrally escaping from the installation frame body after being impacted by external force and deformed, and the safety performance of the window fastening structure is greatly improved. According to the armored car window fastening structure with the explosion preventing and buffering functions and the fastening method thereof, an elastic buffering part and a sliding buffering part are adopted for playing a very effective buffering role immediately after the transparent window is impacted by explosion and the like, the breaking time can be obviously shortened after the window is impacted, the breaking probability can be obviously reduced after the window is impacted, and the safety protection performance of the whole armored car transparent window structure is further improved.