The invention provides an adjustable gun aiming device which comprises an aiming hole seat component, a sliding block body and a sleeve component which are arranged in sequence from front to rear; the aiming hole seat component is in fastened connection with the sleeve component after penetrating through the sliding block body, and the axis of the aiming hole seat component and the axis of then sleeve component are located on the same straight line; an up-down adjustment mechanism is arranged above the sliding block body, a dovetail connection mechanism is arranged below the sliding block body, and the up-down adjustment mechanism is in fastened connection with the sliding block body and is used for adjusting the up-down displacement of the aiming hole seat component, the sleeve component and the sliding block body; the dovetail connection mechanism is fixedly connected with the up-down adjustment mechanism after penetrating through the sliding block body and is fixed to a gun body through a sliding chute; and the left and the right of the sliding block body are provided with leftwards-rightwards adjustment mechanisms, the leftwards-rightwards adjustment mechanisms are fixedly connected to the sliding block body and are used for adjusting the leftwards-rightwards displacement of the aiming hole seat component and the sleeve component. By means of the adjustable gun aiming device, precise positioning of the aiming device can be achieved, stability and reliability of the aiming device are achieved, rapid and precise resetting can be achieved after shooting vibration, and aiming precision and the shooting hit rate are guaranteed.