Based on the monitoring and remediation optimization system (MAROS) platform，the groundwater pollution monitoring networkhas been optimization designed in a certain petroleum hydrocarbon contaminated site in the Northeast China. The single-well concentrationtrend in the region and spatial moment of the polutant in the network，redundancy of monitoring wells and the effectiveness of single-well 'sfrequency were analyed using mathematical statistical methods，Delaunay methods and revised CES approaches，respectively. All of theseresuls helped us made decision of the groundwater monitoring network optimization designed plan in the studly area by combining with theoptimization resuls of monitoring network based on the platform of MAROS.During the study , the related factors with their uncertainties whichaffected the design of groundwater monitoring network have been analysis. The results show that there are five redundancy samplin wells in groundwater polltion monitoring network, and sampling frequency of wells would be changed to 4 timeslyear，1 timelyear，1 time/2year ornone based on the concentration trend，spatial distribution and redundancy of monitoring wels.This work can not only improve the monitoringefficiency of the groundwater monitoring network，but also reduce the monitoring costs. It has importance meaning for guiding the prevention and remediation of groundwater pollution.