The invention discloses a method for rapidly and accurately measuring the specified length of low-cost steel. The method includes the work procedures of datum orientation, measurement and standard comparison, firstly, a datum sheet is temporarily fixed to one end of the detected steel, tightly attached to the
cut section of the detected steel, and kept parallel to the
cut section, and the face, tightly attached to the detected steel, of the datum sheet serves as a measurement datum plane; a
laser length
measuring instrument is tightly attached to the other end, where the datum sheet is not fixed, of the detected steel, a measuring face of the
laser length
measuring instrument is kept parallel to the
cut section, measurement can be conducted, the distance between a point, emitting lasers, of the
laser length
measuring instrument and the datum plane at the other end is the measuring distance, and the datum sheet is detached after measurement is conducted; a measurement result is recorded and compared with a standard so that whether the
actual length of the steel meets the requirement for the specified length of the standard or not can be judged. The method for rapidly and accurately measuring the specified length of the low-cost steel can be conducted through single-person operation, measurement efficiency, stability and stability are comprehensively improved, investment is small, the method can be used for a long time, and the popularization value is high.