The invention relates to the technical field of a neutron scattering spectrometer and particularly relates to a neutron insertion piece system and a collimation mounting method thereof. The system comprises a neutron insertion piece, an inner adjusting mechanism in a shielding cylinder, and an outer adjusting mechanism outside the shielding cylinder, wherein the neutron insertion piece is mounted in the shielding cylinder, the inner adjusting mechanism is mounted at a bottom portion of the neutron insertion piece, the outer adjusting mechanism is arranged on a transition steel plate, the transition steel plate is pre-embedded in a concrete base station, and the neutron insertion piece is conveyed in and out of the shielding cylinder through the outer adjusting mechanism. The neutron insertion piece system is advantaged in that the structure is relatively simple, strong machinability and adjustability are realized, the deviation relationship of an actual value and a theoretical value of a target set can be acquired, update and maintenance of the neutron insertion piece are facilitated, a collimation mounting apparatus is a laser tracker and a measurement arm, collimation and mounting of the neutron insertion piece can be rapidly and conveniently realized, and replacement of the neutron insertion piece can be realized in minutes.