This paper is focussed on investigating the effect of linear time delay on vibrational resonance of a harmonically trapped potential system driven by a biharmonic external force with two wildly different frequencies$\omega$ and $\Omega$ with $\omega \ll \Omega$. Firstly, the approximate analytical expression of the response amplitude $\mathcal{Q}$ at the low frequency $\omega$ is obtained by means of the direct separation of the slow and fast motions, and then we verified the numerical simulation by using the fourth-order Runge–Kutta method and found that it is in good agreement with the theoretical analysis. Next, the influence of the time-delay parameters on the vibrational resonance are discussed. There are some meaningful conclusions. If $\tau$ is a controllable parameter, the response amplitude $\mathcal{Q}$ not only exhibits periodicity but also can be amplified via the cooperation of $F$ and $\tau$ . If the time-delay intensity parameter $r$ is a controllable parameter, the response amplitude $\mathcal{Q}$ is found to be much larger than that in the absence of time delay. Moreover, adjusting $r$ can result in a better response than adjusting $\tau$ . This undoubtedly gives us a superior way to amplify the weak low-frequency signal.