In this paper, we proposed a fractional-order microscopic chaotic system, derived from a set of microscopic chemical reactions. The dynamical properties of the proposed model have been investigated through Lyapunov characteristic exponents, bifurcation, spectral entropy and C0 complexity algorithm. The results show that the system has rich dynamics in derivative order and the system parameter. In addition, multiple coexisting attractors are found in the system by selecting appropriate initial values. Complexity measuring algorithms are developed as an effective tool for the detection of such attractors. The results are effective for the dynamical randomness in the collisional motion of atoms and molecules in fluids to produce the deterministic chemical chaos, even in fractional order.