Abstract: Straw biochar has various positive effects on soil ecology and environment improvement, soil water and fertilizer conservation, and reduction of greenhouse gas emission. But the release of carbonate from some calcium carbonate (lime) can increase pH and hence ammonia (NH3) volatilization in paddy fields. In this study, a two-year potted experiment with a completely randomized design was conducted using different biochar for better ammonium absorption while less impact of lime. The japonica rice (Oryza sativa L. cv. Da Li Nuo) and biochar deriving from rice straw were taken as the research objects. Three pyrolysis temperatures (300, 500, and 700 ℃) and three levels of acidification (5, 7, and 9) were selected in the experiment. Prior to the test, the surface soil in the rice field was sampled and then air-dried. Biochar and basal fertilizer were applied one day before transplanting. The concentration of ammonium nitrogen in surface water, ammonia volatilization loss from a paddy field, and rice grain yield were measured under different biochar treatments during two rice growing seasons. The results showed that the ammonia volatilization loss ranged from 30.27 to 52.1 kg/hm2 (2019), and 30.20 to 38.00 kg/hm2 (2020) in the rice fields during rice growing stages, accounting for 15.14%-26.05% of N application rate (2019), and 15.1%-19.0% (2020). High temperature pyrolysis with acid and neutral straw biochar significantly reduced the volatilization loss. Biochar at pyrolysis temperature of 700 ℃, acidification level 5 (C700P5) presented the best performance of ammonia reduction, where the ammonia volatilization was significantly reduced by 22.93% and 12.61% in 2019 and 2020, respectively. The variation trend of NH4+-N concentration in field water was consistent with that of NH4+-N volatilization flux. The peak NH4+-N concentration in surface water decreased by 16.90%-35.60% in the basal and tillering stages with acidic and neutral straw biochar. The acidic and neutral rice straw biochar significantly increased the rice aboveground N accumulation by 9.10%-24.84% at three pyrolysis temperatures. High temperature pyrolysis combined with acid and neutral biochar (C700P5, C700P7) presented a significant yield increase, where the yield increase rate was 9.92%-13.50%. The structural equation showed that there were positive and negative effects of biochar pH value and Cation Exchange Capacity (CEC) on ammonia volatilization, whereas, together with an obvious lime effect. But the obvious adsorption was to inhibit ammonia volatilization. In addition, the ammonia volatilization in the paddy field was significantly correlated with NH4+-N concentration in surface water. The effect of biochar on ammonia volatilization was also described in the regulation on NH4+-N concentration in surface water. The combination of neutral and acid improvement with high temperature pyrolysis biochar (C700P5, C700P7) increased production, because both ammonia volatilization and nitrogen loss reduced significantly, particularly providing for more sufficient nutrients for the growth of rice. This finding can offer the potential application of biochar at different pyrolysis temperatures and acidification levels in rice fields.