The utility model relates to a railway track measuring device especially relates to an accurate torn -up device of railway track that detects. Under the auxiliary stay of bracing piece (1), data acquisition drives laser displacement sensor (6) with processing unit (2) control power unit (5) and at the uniform velocity removes in the guide rail mechanism (4) that installs grating displacement sensor (3), laser displacement sensor (6) and grating displacement sensor (3) are real -time measurement railroad section size and lateral shifting volume respectively, the cooperation laser displacement sensor of reflector mechanism (7) (6) accomplishes the measurement of rail jaw size, data acquisition handles through data analysis with processing unit (2), and railway track wearing and tearing volume is saved to the refined calculation. The utility model discloses a to the measurement of rail jaw size, the refined calculation of rail wear value is accomplished to effective location of realization measuring basis, improves the torn -up measurement accuracy of railway track greatly.