The invention relates to a visual detection device used for a fine long cavity body, belonging to the visual detection device. The problem that an end photographing system can not precisely position is solved and simultaneously the cost is lowered. The detection device comprises a base, a lifting mechanism, a motion mechanism and a photographing system. The vertically directional displacement of the motion mechanism is adjusted by the lifting mechanism to lead to the coaxial type of a probing rod and the cavity body to be detected. The motion mechanism comprises the probing rod, a probing rod hollow sleeve, a central gear, a probing rod supporting base, a translational motor cabinet, a rack, a translational motor gear, a motion supporting station, a rotary motor gear, a rotary motor and a translational motor. The photographing system is arranged on the probing bar end of the motion mechanism and comprises a supporting board, a photographer, a prism and a light source. Based on the design of a cylindrical coordinates, the device has the advantages of circumferential rotation, axis translation, radial fine adjustment, small gyration radius, long axial stroke, good rigidity and convenient processing and manufacturing. The visual detection device is applied to the assembling, the painting or the welding quality detection of fine long cylindrical cavity body which is not sealed or is provided with one sealed end and can not be reached by human.