The invention relates to a controllable section sealing device used for the sealing of a downhole tool and a downhole working barrel, comprising a barrel-shaped shell; the controllable section sealing device also comprises a sliding-sleeve driving mechanism installed in the barrel-shaped shell, seal housings fixedly sheathed on the outer wall of the barrel-shaped shell, and sliding sleeve sheathed on the outer wall of the barrel-shaped shell in a sliding way; the seal housing is provided with a bowl-mouth-shaped elastic flaring opening which is correspondingly arranged with the sliding sleeve and left with a clearance which is capable of being inserted by the sliding sleeve so as to open the lip clearance of the elastic flaring opening together with the barrel-shaped shell, the seal housings are arranged on the barrel-shaped shell in pairs, two seal housings arranged in pairs are arranged at two ends of one section of the barrel wall, and the sliding sleeves are also arranged in pairs and correspond to the pair of seal housings. The controllable section sealing device realizes the interference sealing with the working barrel and the controllable sealing and long-term monitoring of the formation pressure through the deformation of the seal sleeve, thus causing higher application value of a test file.