An alignment adjust device (100) for a multi-modality imaging system and an alignment adjusting method thereof. The multi-modality imaging system comprises a positron emission tomography (PET) imaging system and other imaging systems. The alignment adjusting device comprises two target stands (110) perpendicularly disposed to the ground and a main support mechanism (120) for mounting and fixing the target stands (110) or a PET frame. The two target stands (110) are parallel to each other, and a connection direction of a target indicates an axial direction of the PET imaging system. The main support mechanism (120) comprises an adjustment base (121), and a frame base plate (122) disposed on the adjustment base (121) and used for mounting and fixing the target stands (110) or the PET frame the adjustment base (121) is used for adjusting a distance between different positions of the frame base plate (122) and the ground, such that the targets of the two target stands (110) coincides with a central axis of the other imaging systems the PET frame is mounted on the adjusted main support mechanism (120). The device is structurally simple and enables fast, easy and effective movement and alignment processes, thus effectively ensuring that the requirement for a PET detector to be centrally coaxial with the other imaging systems can be fulfilled.Linvention concerne un dispositif de réglage dalignement (100) pour un système dimagerie à modalités multiples et un procédé de réglage dalignement associé. Le système dimagerie à modalités multiples comprend un système dimagerie par tomographie par émission de positrons (TEP) et dautres systèmes dimagerie. Le dispositif de réglage dalignement comprend deux montants cibles (110) disposés perpendiculairement au sol et un mécanisme de support principal (120) pour monter et fixer les montants cibles (110) ou un cadre TEP. Les deux montants cibles (110) sont parallèles lun à lautre, et une direction de connexion dune cible indique une di
