Abstract: The slight-stretch sizing (reducing) mill is a key unit of the hot-rolled pipe production line. To satisfy the demand for various product types,normally a great number of roll stands are provided for such mill by the pipe maker. Based on the TZ355 roll stand,the roll stand structural characteristics of the said sizing mill is elaborated,and the key elements affecting the assembling accuracy of the roll stand analyzed. Accordingly proposed are the assembling process,the adjustment method,and the method for verifying of the assembling accuracy of the roll stand.