The invention discloses a single-droplet spontaneous combustion detection device and method. The device comprises a monochromator, a photomultiplier, a high-voltage power source, a high-speed data acquisition card, a collimating lens and an optical fiber bundle; the collimating lens converges optical signals around a single liquid drop to the inlet end of the optical fiber bundle; the optical signals are transmitted through the optical fiber bundle and enter the monochromator; the monochromator filters wide-spectrum optical signals, so that only optical signals with specific wavelength can enter the photomultiplier; and the photomultiplier converts the optical signals with the specific wavelength into amplified electric signals; and the amplified electric signals are stored in the high-speed data acquisition card. The device has the advantages of low price and high sensitivity. With the single-droplet spontaneous combustion detection device and method of the invention adopted, researchon a single-droplet spontaneous combustion problem in a low-temperature environment can be benefitted.