Under neutral medium,manganese( II) could obviously quench the fluorescent intensity of levofloxacin. Based on this,a fluorescent spectral method for the detection of trace manganese( II) was developed. Under the optimal experiment conditions,fluorescent intensities with a small amount of manganese( II) and control were tested. It was found that the fluorescent quenching intensity was proportional to the concentration of manganese( Ⅱ) in the range of 2. 5 × 10-7~ 1. 0 × 10-5mol / L with the relative standard deviations of less than 5%. The limit of detection was as low as 8. 4 × 10-8mol / L( S / N = 3). This method was applied to detect the content of manganese( Ⅱ) in three vegetable samples with satisfactory results.