In biological fluorescence imaging, obtaining high spatial-temporal resolution volumetric images under low light conditions is one of the critical requirements. As a widely-used snapshot volumetric imaging modality, light field microscopy has the problem of impeded imaging performance caused by reconstruction artifacts, especially under low light conditions. Fortunately, low-rank prior-based approaches have recently shown great success in image, video and volume denoising. In this paper, we propose an approach based on the spatial-temporal low-rank prior combining weighted nuclear norm minimization (WNNM) denoising and phase-space 3D deconvolution to enhance the performance of light field microscopy (LFM) under low light conditions. We evaluated the method quantitatively through various numerical simulations. Experiments on fluorescence beads and Drosophila larvae were also conducted to show the effectiveness of our approach in biological applications.