An allsolidstate nitrate doped polypyrrole (PPy(NO-3) ionselective electrode (ISE) was prepared with a nanohybrid composite film of gold nanoparticles (AuNPs) and electrochemically reduced graphene oxide (ERGO). Preliminary tests on the ISE based insitu soil nitrate nitrogen (NO-3N) monitoring was conducted in a laboratory 3stage column. Gold nanoparticles (AuNPs) and electrochemical reduced graphene oxide (ERGO) nanocomposite were used to improve the stability, sensitivity, and lifetime of ISE. The electrode life was significantly improved, and the average response slope was 44.02mV/dec within 65 days. The relationship between soil depth, soil texture, soil moisture, and soil nitrate nitrogen content of percolate was analyzed by the insitu realtime monitoring system of soil percolate. The results showed that different soil depth, texture, and moisture had no effect on the detection of nitrate nitrogen concentration in soil exudate. The nitrate nitrogen was significantly affected by the sampling depth, which was raised by 30~60mg/L with a depth increase of 10cm. the influence of water content was not obvious. The soil particle size of 2.5mm was the influence pole. The influence was not obvious when the particle size was smaller than 2.5mm, while the nitrate nitrogen concentration was decreased by 19.5% in soil percolate solutions with particle size larger than 2.5mm. The determination results of nitrate nitrogen in tested percolate samples by ISE and UV-VIS methods were in good agreement. Obvious differences of 5~6 times concentrated nitrate nitrogen concentration were found between the insitu percolate samples and conventional soil extracts. 