We propose a kind of hybrid plasmonic Fabry-Perot (F-P) microcavity consisting of ZnO microwires with quadrate cross-section and planar multilayer metal-insulator-metal (MIM) homostructures with a nanoscale SiO₂ gap in between. MIM homostructures can be used to create a micro-resonator that simultaneously provides feedback for laser action and supports the coupling between the plasmonic waveguide modes and microwire modes across the gap. The hybridization of ZnO microwire modes and surface plasmons across the gap forms hybrid plasmonic F-P microcavity modes, which are highly confined to the low-loss SiO₂ gap region. By comparing with bare ZnO microwires, an enhancement in photoluminescence (PL) intensity of two orders of magnitude is realized experimentally due to the coupling between plasmonic MIM homostructures and ZnO microwires. The controllability and miniaturization emission properties of this type of microcavity are potentially important for designing laser cavity applications and information transmission.