Flow-injection chemiluminescence was applied to determine the trace polyhydroxy phenol in environment (soil and water). Based on the comparison of several different chemiluminescence systems and optimization, an alkaline luminol-NaIO4 system for determinating polyhydroxy phenol was chosen. During the process of polyhydroxy phenol determination, the effect of dissolved humic acid (HA) on the determination of phenol by this chemiluminescence system was also considered, which generally coexists in soil and water widely. Thus the present work provided the reference for the determination of the real samples coming from soil or water. An obvious restraining effect of humic acid on the chemiluminescence signal obtained by the luminol-NaIO4-polyhydroxy phenol system was found, which shows a linear relationship with the concentration of HA in a certain range, the linear equation is y = 70.36x + 540.1, the correlation coefficient is 0. 9954, the linear range is between 3-15 mg x L(-1), the limitation of detection is 0.749 mg x L(-1), and the relative standard deviation (RSD) is 1.08% when the concentration of HA is 6 mg x L(-1). The possible working mechanism of humic acid here is discussed and deduced.