In view of a solution of the stability issue of networked sampling control systems in environments with uncertain communication delays, a bilateral closed-loop function method has been adopted to apply unique bilateral closed-loop cyclic functionals in each sub-interval with the sampling interval divided into two subintervals. Then, with an addition of several zero equations considering the intrinsic relationship of the system state vector, a low conservative stability criterion can be obtained in the form of linear matrix inequality (LMI) by using the technique of free matrix integral inequality. Finally, numerical examples are given to verify the stability criterion, with the simulation results confirming the effectiveness and superiority of the proposed method.