Code-switching refers to the process of mixing different language features within a single passage that may cause a contrasting effect. This study aims to reveal the grammatical constraints on intra-sentential code-switching in the case of Bahasa Indonesia-Chinese by collecting the data of code-switching of 14 Indonesian students in Tianjin. The result finds that The language model in the case of Bahasa Indonesia-Chinese code-switching shows that Bahasa Indonesia is the dominant language for most cases. However, the switched with the same structure with Chinese, and have the same frequent occurrence of morpheme cannot be assigned into the ML and EL, only switched cases with system morpheme, and Bahasa Indonesia is the frequent morphemes can be accounted into ML or EL. The cases of switched sentences between the aspect of time and verb answer the assumption that a switch may occur even at the surface structure of the participant languages that do not map onto each other. Moreover, the free morpheme constraint analysis using the minimalist program, the bound morphemes of Bahasa Indonesia that denote determiner and possessive, can be cut from its position to project the maximal projection in VP, and still, retain a free morpheme. This finding does not violate the free morpheme constraint theory. However, the passive form switched shows that a switch occurs between bound morpheme and the lexical. The bound morpheme cannot be cut and retain a free morpheme. The switched sentences that are analyzed by the minimalist program, moreover, the result finds that when the bound morpheme cut from its position to retain a free morpheme, it falls under the lower constituent under PP.