Let $\{X_n,n\ge 1\}$ be a sequence of $m$-dependent strictly stationary random variables in a sub-linear expectation $(\mathrm{\Omega },\mathcal{H},\mathbb{E})$. In this article, we give the definition of $m$-dependent sequence of random variables under sub-linear expectation spaces taking values in $\mathbb{R}$. Then we establish moderate deviation principle for this kind of sequence which is strictly stationary. The results in this paper generalize the result that in the case of independent identically distributed samples. It provides a basis to discuss the moderate deviation principle for other types of dependent sequences.