Smart contracts have attracted increasing attention with the continuous development of Blockchain. However, the uncertain status in law severely limits their practical applications. So, Smart Legal Contract (SLC) is proposed as a bridge between legal contracts and smart contracts. Starting with basic concept of smart contract, in this paper we discuss SLC’s legalization and point out that the legalization should meet three elementary principles, including the specified grammatical requirements, the principle of non-empowerment, and the examination criteria, and then analyzes SLC’s legal effect by taking smart legal contract language as an example. Moreover, analyzing in several smart contract architectures, we demonstrate that either smart contract program or the corresponding Chaincode is a kind of data messages in written form, but it is not a legal contract itself. Further, in order to ensure that the above program or Chaincode has the same legal effect as the original contract, three conditions, adopting the generation and conclusion of SLCs, complying with three elementary principles mentioned above, and agreeing on declaration with the same legal effect, need to be met. Our research shows that the SLC is a feasible way to guarantee the legal status of smart contract, and it is also conducive to grasp the future research directions in several fields, e.g., contract logic, arbitration process, and formal verification, from the perspective of existing legislation.