In this article, we study the following fractional critical Schrödinger system \(\begin{aligned} {\left\{ \begin{array}{ll} (-\Delta )^s u_i=\mu _iu_i^3+\beta u_i\sum _{j\ne i}u_j^{2}+\lambda _iu_i &{}\text { in } \ \Omega ,\\ u_i=0 &{}\text { on } \ {\mathbb {R}}^N\setminus \Omega , \end{array}\right. } \quad i=1,2,\ldots ,m, \end{aligned}\) where \(0<s<1\) , \(\mu _i>0\) , coupling constant \(\beta \) satisfies either \(-\infty <\beta \le {\bar{\beta }}\) ( \({\bar{\beta }}>0\) small) or \(\beta \rightarrow -\infty \) , \(0<\lambda _i<\lambda _1^s(\Omega )\) , where \(\lambda _1^s(\Omega )\) is the first eigenvalue of \((-\Delta )^s\) on \(\Omega \) , with \(\Omega \) is a smooth bounded domain in \({\mathbb {R}}^N\) with \(N=4s\) . Under some geometric assumptions on \(\Omega \) , we construct solutions which concentrate and blow up at different points as \(\lambda _1,\ldots ,\lambda _m\rightarrow 0\) .