For a class of second-order multi-agent systems with a fixed and undirected communication topology and uniform delays systems, linear consensus protocols with time-delayed communications are adopted, the stability conditions are analysised. As the order of system is very high, the stability analysis of the characteristic equation becomes intractable. This paper proposes a new analysis approach via decomposing the characteristic equation of system into a set of factors and using the CTCR method, derives the communication delay of each eigenvalue, and obtains the accurate upper bound of delay of the system. We also explore the stability region generated through the protocol. The results show that in a case of a spanning tree, when time delay is less than the decision value, the stability of the system can be achieved. Finally, numerical simulation shows the effectiveness of the results.