A pair of fluorescent molecules capable of producing fluorescence resonance energy transfer (FRET) were used as donor and acceptor dyes. The polarization properties of FRET optical microfluidic lasers were investigated based on the G-quadruplex structure of deoxyribonucleic acid (DNA) molecules using a Fabry-Perot (F-P) microcavity as an optical resonance cavity. In the experiment, five solutions of DNA of varying K⁺ concentrations (whose molecular ends are each labeled with a pair of fluorescent dyes that can produce FRET) were studied and excited with linearly polarized pump light, and the ratio of the slope of the laser threshold curve of the acceptor in the parallel polarization direction (parallel to the pump light polarization direction) and the slope of the laser threshold curve (SER) in the vertical polarization direction (vertical to the pump light polarization direction) was used as the detection signal of the laser polarization of the acceptor. Findings indicate that as the K⁺ content in the DNA solution increases, the pumping threshold of the acceptor laser decreases, energy conversion efficiency improves, and the slope ratio of the acceptor laser reduces, leading to decreased polarization.