The influence of time-injection velocity on the miscible displacement in porous media is studied numerically. We examined the scenario when a more viscous fluid of finite length is confined within a less viscous one in a Hele-Shaw cell. The injection velocity is assumed to be in form of a sinusoidal form characterized by its amplitude (Γ) and time-period (T). The physical mechanism is analysed by solving three coupled equations, namely, Darcy’s equation, continuity equation and convection-advection equation. The non-linear simulations for the rectilinear flow have been carried out using COMSOL multi-physics (version 5.3a). The obtained results suggest that for Γ < 0, the fingering can be suppressed whereas Γ > 0, yields in vigorous fingers as compared to when Γ = 0 (the constant injection strategy). It can be concluded that the timedependent strategy may help in analysing and controlling the spread of contaminants and chemical separations.