A distance measuring device, comprising: a first housing; and a laser ranging device, provided at the inside of the first housing; wherein the laser ranging device comprises a laser generating means, adapted to emit a measurement beam to an object to be measured, such that the measurement beam is reflected by the object to be measured, generating thereby reflected light; a photoelectric conversion means adapted to capture all or part of said light reflected by the object to be measured and to convert the optical signal of the captured reflected light into at least one feedback electrical signal; a circuit board on which at least one processor is provided; and a power supply connected to the laser generating means, the photoelectric conversion means and the circuit board; wherein the processor is connected to the laser generating means for controlling the laser generating means; the processor is connected to the photoelectric conversion means for acquiring the feedback electrical signal and calculating a distance from the object to be measured to the distance measuring device; wherein the distance measuring device further comprises a tapeline disposed within a second housing which is detachably connectable to the first housing; characterised in that the distance measuring device further comprises an outer casing, which is a transverse U-shape; and the outer casing comprises: a first outer casing through hole extending through a top surface of the outer casing; a second outer casing through hole extending through a right side face of the outer casing; a third outer casing through hole extending through a bottom surface of the outer casing; a first outer casing notch provided on a left side face of an upper portion of the outer casing; and a second outer casing notch provided on a left side face of a lower portion of the outer casing; and wherein the first housing and the second housing are covered by the outer casing when the second housing is connected to the first housing. a first housing; and a laser ranging device, provided at the inside of the first housing; wherein the laser ranging device comprises a laser generating means, adapted to emit a measurement beam to an object to be measured, such that the measurement beam is reflected by the object to be measured, generating thereby reflected light; a photoelectric conversion means adapted to capture all or part of said light reflected by the object to be measured and to convert the optical signal of the captured reflected light into at least one feedback electrical signal; a circuit board on which at least one processor is provided; and a power supply connected to the laser generating means, the photoelectric conversion means and the circuit board; wherein the processor is connected to the laser generating means for controlling the laser generating means; the processor is connected to the photoelectric conversion means for acquiring the feedback electrical signal and calculating a distance from the object to be measured to the distance measuring device; wherein the distance measuring device further comprises a tapeline disposed within a second housing which is detachably connectable to the first housing; characterised in that the distance measuring device further comprises an outer casing, which is a transverse U-shape; and the outer casing comprises: a first outer casing through hole extending through a top surface of the outer casing; a second outer casing through hole extending through a right side face of the outer casing; a third outer casing through hole extending through a bottom surface of the outer casing; a first outer casing notch provided on a left side face of an upper portion of the outer casing; and a second outer casing notch provided on a left side face of a lower portion of the outer casing; and wherein the first housing and the second housing are covered by the outer casing when the second housing is connected to the first housing. a first outer casing through hole extending through a top surface of the outer casing; a second outer casing through hole extending through a right side face of the outer casing; a third outer casing through hole extending through a bottom surface of the outer casing; a first outer casing notch provided on a left side face of an upper portion of the outer casing; and a second outer casing notch provided on a left side face of a lower portion of the outer casing; and wherein the first housing and the second housing are covered by the outer casing when the second housing is connected to the first housing.