The invention belongs to the field of pipeline maintenance engineering, and particularly relates to a construction device and method for integrated construction of small-diameter pipeline maintenance.The construction device and method are mainly applied to site maintenance of small-diameter pipelines, and integrated construction of pipeline centering and pairing, groove cutting and automatic welding can be achieved. The device comprises a fixing frame, a vertical supporting frame, an extension section, a lifting section, a slip, a split beveling machine and an open type automatic welding machine. According to the construction device and method, the design that a pipeline is clamped and fixed through a V-shaped block, a replacement pipe section is fixed through a chain, and a plurality ofsections are spliced into an integral beam is adopted, so that the construction device and method can adapt to different pipe diameters and pipe span widths, and the problems that an existing productcannot be suitable for site maintenance of small-diameter pipelines, construction components are independent, and the construction precision and efficiency are low are solved. By means of the advantages of the existing product, function integration of the existing product is achieved, the structure is novel and compact, the engineering efficiency is improved, and the practical value of the construction device is achieved.