The invention discloses a
train safety speed measuring device and method and a
positioning system, and the device comprises a plurality of speed
measuring instrument combination mechanisms, and each speed
measuring instrument combination mechanism comprises at least two
laser speed measuring instruments; the support comprises at least two supporting rods, one ends of the at least two supporting rods or extension lines of the ends of the at least two supporting rods have an intersection point, the included angle between any two supporting rods is fixed, and the at least two
laser velocimeters and the at least two supporting rods are arranged in a one-to-one correspondence mode; the ejector rod is located at the top of the support, and the ejector rod is connected with a
train bogie; and a
laser beam of each laser velocimeter corresponds to a rail surface of a
train rail. The speed of the train is directly measured, the
speed measurement error caused by wheel idling and slipping is avoided, the
speed measurement precision is improved, the positioning precision of the train is improved, the
safety margin is shortened, and the operation efficiency is improved.