Abstract: In order to clarify the effect of biogas slurry replacing the chemical fertilizers on heavy metal in the production system of paddy field in the protection and development belt surrounding Wuyishan National Park four treatments including 100% chemical fertilizer (T₁), 50% chemical fertilizer+50 biogas slurry (T₂), 50% chemical fertilizer+100% biogas slurry (T₃), and 50% chemical fertilizer+200% biogas slurry (T₄) were set up by using the paddy field of single-cropping rice in Shantou Village of Guangze County as the sample plot. The ecological risk index (P_i) of rice was evaluated by using the single factor, and the potential ecological pollution risk index (R_I) of heavy metals in soil was evaluated by using the Hakanson method. The results showed that: the risk of heavy metals was not found in the experimental rice, No risk of heavy metals was found in the experimental rice, among which P_Cd was less than 0.005, P_Hg ranged from 0.450 to 0.700, P_Cr ranged from 0.009 to 0.014, P_As ranged from 0.080 to 0.166, and P_Pb ranged from 0.110 to 0.325.The potential ecological pollution risk index (RI) of soil heavy metals ranged from 203.5 to 269.9, and the main pollution risks came from Hg and Cd. The relative enrichment coefficients of the two heavy metals were 227.0%-349.2% and 250.0%-363.3%, respectively. Compared with the indicators before planting, R_I of T2 treatment increased by 11.9, but R_I of T1, T3 and T4 treatment decreased by 56.9, 11.3 and 18.2, respectively. The potential ecological pollution risk of T2 treatment was mainly Cd.