Abstract: A field investigation and an epidemiological investigation were carried out on four workers being suspected methanol poisoning victims in a precision metal products factory in Kunshan City. The time weighted average permissible concentration of methanol in the highlight station reached 482.9mg·m^-3, significantly higher than the national occupational exposure limit (50mg·m^-3). Without installed local ventilation facility, these victims reported not wearing effective personal protective equipment and not having pre-job occupational health examination. Besides, the third-party technical service suppliers failed to identify and detect methanol. Such factors contributed to the four victims' neurologic signs and blurred vision after inhaling high-concentration methanol.