Disclosed are a low-mold deposit halogen-free flame-retardant thermoplastic polyamide composition, and a preparation method and use thereof. The low-mold deposit halogen-free flame-retardant thermoplastic polyamide composition of the present disclosure includes the following components in parts by weight: 20 to 82 parts of a thermoplastic polyamide resin; 13 to 25 parts of a flame retardant; 1 to 5 parts of a flame-retardant synergist; 5 to 50 parts of a reinforcement material; and 0.5 to 5 parts of an adsorbent, where the flame retardant includes a phosphinate-based flame retardant and the adsorbent is an ethylene copolymer. In the low-mold deposit halogen-free flame-retardant thermoplastic polyamide composition of the present disclosure, an ethylene copolymer is added as an adsorbent and an addition amount of the ethylene copolymer is controlled, so that the prepared low-mold deposit halogen-free flame-retardant thermoplastic polyamide composition exhibits excellent flame resistance and electrical properties, and can effectively reduce the release of small molecules during the injection molding and greatly reduce an amount of the mold deposit generated during the injection molding.