摘要：Reactor neutrino experiments build large-scale detector systems to trap ghost-like neutrinos. In liquid scintillator, a neutral bound state of a positron and an electron named positronium could be formed. The spin triplet state was called ortho-positronium (o-Ps). In this script, an experiment was designed to measure the lifetime of o-Ps, which turned out to be 3.1 ns. A PSD parameter based on photon emission time distribution (PETD) was constructed to discriminate e+/e−. Finally the application of e+/e− discrimination in JUNO experiment was shown. It helps suppression of 8He/9Li backgrounds and improves the sensitivity by 0.6 in χ2 analysis with assumption of σ=1 ns PMT Transit Time Spread, which will bring smearing effect to PETD.