In this paper, superlens imaging with surface plasmon polariton cavities in both object and image space is proposed and investigated. A silver layer is added to an object mask to form a surface plasmon polariton (SPP) cavity in object space, which helps to greatly enhance evanescent waves generated by objects. As a result, better object imaging contrast can be obtained when compared with the single surface plasmon polariton cavity in image space only by amplifying the higher frequency componments while suppressing the long range plasmon mode. This is confirmed by the electric field distributions and optical transfer function of the system. The physical mechanism of the imaging quality improvements based on surface-plasmon polaritons is discussed. Finite-difference time-domain analysis method is used in the simulation.