Trivalent rare-earth (RE)-doped upconversion photoluminescence (UCPL) materials are promising in solar cell, anti-fake printing, and displays. However, the intensity of UCPL is often not high enough for practical applications, because of very weak absorption cross-section at the pump wavelength due to the parity forbidden intra-4f shell transitions of RE ions. One promising approach for the enhancement of UCPL efficiency is exploiting the coupling of RE-doped upconverters with surface plasmon resonance of a metal nanostructure. In this paper, we report lithographically fabricated two-dimensional square lattice of Al nanocylinders combined with nanoparticles layer of CaF2 codoped with Er3+,Yb3+ that shows enhanced UCPL. We systematically vary the periodicity of the lattice and examine the UCPL enhancement. The maximum UCPL enhancement is observed at a period of 750 nm, showing 22 and 13.3-fold enhancements for green and red emission branches, respectively. Moreover, we observe enhancement of downconversion emission at 1540 nm. A comparison between the experiment and simulation suggests that enlarged light absorption at the pump wavelength is a dominant factor for UCPL and downconversion enhancements.