The phase and velocity sensitivity is calculated at the interface of three level atomic medium and a Silver Silica (AgSiO2) nano-composites material by surface plasmon polaritons waves. A large kink in the real part of dispersion relation of SPPs is measured in the large interaction zone, due to which the group velocity and delay/advance times of SPPs are enhanced. A group velocity of v g = ±1 × 109 m s−1 is measured at the group index region of 0 < n g < 1 and −1 < n g < 0. The propagation time is measured to be t g = ±1 × 10−7 s at the propagation length L x (m) and at v g = ±1 × 109 m s−1 in the range of group index of 0 < n g < 1 and −1 < n g < 0. The volume fractional change of nano particles, probe/control field detuning and Rabi frequency of control field significantly influence the velocity sensitivity. The velocity sensitivity is measured to be 23 μm s−1 by SPPs. The velocity sensitivity could be improved to 0.1 μm s−1 by taking large ensemble of atomic coherence and large delay/advance in time due to SPPs.