A new kind of double-tube construction of coriolis type mass now meter with straight sensor tube is presented in this paper. It avoids the defect of additional error caused by the difference character of two tubes in the construction of double measuring tubes and the defect of error caused by the vibration of the base in the construction of single measuring tube. The principle of the new construction and the realisation method is discussed in this paper in detail, moreover, the new doubletube construction is realized, and very good performance is achieved-