By adopting the time-dependent continuous Lyapunov-Krasovskii functional method, a research has been carried out on the stability of the linear sampled-data systems. Based on the existing free-matrix-based integral inequality (FMBII), a new FMBII, which is suitable for sampled-data control of system, has been proposed. A sufficient condition for the stability of sampled data systems is to be obtained by using the inequality to deal with an integral term, thus working out the sufficient condition that can guarantee the stability of sampled-data system. Four numerical examples are given to testify the efficiency and superiority of the proposed approach.