Crop Circle ACS 430 is a newly developed active crop canopy reflectance sensor with three fixed wavebands covering red (670 nm), red-edge (730 nm) and near infrared (NIR,780 nm) regions. The objective of this study was to determine how much improvement the Crop Circle ACS430 would achieve for estimating rice yield potential at key growth stages as compared with a GreenSeeker sensor. Four N rate experiments were conducted in 2012 and 2013 at Jiansanjiang Experiment Station of China Agricultural University, located in Sanjiang Plain, Heilongjiang Province, Northeast China. The results indicated that in-season estimate of yield (INSEY) calculated with GreenSeeker normalized difference vegetation index (NDVI) and ratio vegetation index (RVI) could only explain 18% and 13% of variability in yield potential without additional topdressing N application (YP0) at panicle initiation stage and there was no significant relationship at heading stage. By comparison, the INSEY calculated with the best Crop Circle vegetation indices explained 35% and 58% of YP0 variability at these two stages, respectively. At stem elongation stage, the Crop Circle ACS-430 sensor (best R2=0.68) did not have any significant improvement over GreenSeeker RVI (R2=0.65). More studies are needed to further evaluate Crop Circle ACS-430 sensor for precision N management of rice under on-farm conditions.