In this paper, we mainly study the stability of linear and interval linear fractional systems with time delay. By applying the characteristic equations, a necessary and sufficient stability condition is obtained firstly, and then some sufficient conditions are deserved. In addition, according to the equivalent relationship of fractional order systems with order $0<\alpha\leq 1$ and with order $1\leq\beta<2$, one may get more relevant theorems. Finally, two examples are provided to demonstrate the effectiveness of our results