Nano metal-organic frameworks (ZIF-8) particles were synthesized, and poly(lactic acid) (PLA)/ZIF-8 nanocomposite films were prepared by solution-blending and film-casting methods. The addition of nano ZIF-8 particles improved the mechanical properties and had an impact on the crystallization of PLA. The electrical properties of the PLA/ZIF-8 nanocomposites were found to be dependent on the frequency and the ZIF-8 content. The prepared PLA/ZIF-8 films had good transparency even as the content of the nano ZIF-8 particles reached 3 wt %. Compared with 21.5% of pure PLA, the limited oxygen index value of the nanocomposite film containing 1 wt % ZIF-8 reached 26.0%. Therefore, it is proposed that the prepared nanocomposites can be used as the substrates and dielectric to make disposable electronics. The char residues after burning were studied in detail by scanning electron microscopy and Raman and X-ray photoelectron spectroscopies, and the flame retardant mechanism was also discussed.