The boundary of garnishment is concerned about the identification of the debtor's liability property and protection of the third party, as well as is of great significance in ensuring the legitimacy of the enforcement. Under the background of codification of civil compulsory enforcement law, the definition of the scope of the object in garnishment is a key issue in promoting the systematic construction of garnishment. The jurisprudential basis for this issue consists of the theory of liability property, the principle of limited enforcement and the principle of benefit balance. According to the theory of liability property, the claim as object in garnishment must be of economic value, independence and transferability, and be owned by the debtor. In order to protect the public interest and respect the human rights, the principle of limited enforcement should be followed, and claims that are prohibited from being transferred under substantive law and claims that are prohibited from being enforced under procedural law should not be enforced. Meanwhile, the principle of benefit balance requires the enforcement agency to balance the interests among multiple subjects, so as to avoid excessive burden for the debtor and the third party. On the whole, the garnishment should be divided into basic type and possession type, and its object forms should be reconstructed on this basis. The former is used to realize monetary claims, the object of which includes undue claims and non-monetary claims. However, the attachment of future claims is subject to certain limitations, which should be considered in the light of the legal relationship underlying the claim, the likelihood of the future claim occurring, and the specificity of the legal subject. As for the continuing claims, its objective scope of attachment extends to claims based on the same legal relationship, and relevant provisions in draft should be amended. The latter is used to realize the claims for delivery of property, and it applies only where a third party owes an obligation of delivery to the debtor. The garnishment shall not be applied if the third party is a successor of the party or is in possession of the subject matter for the benefit of the party or the successor. Compared with foreign countries, the grounds for rejecting the execution of possession type are also special in China, as it is possible to enforce directly against a third party without obtaining a judgement against him.