Configuration and type of front removable barrel is different from non-front removable barrel, and configuration of each type of front removable barrel is also different. Because of support directional situation of barrel recoil and counter-recoil is different, so influence on gun fire dispersion is different. According to connecting method of front removable barrel and non-front removable barrel of tank gun, different influences for two types of configuration on gun fire dispersion are analyzed. This method provides reference basis for configuration design of front removable barrel.