In order to explore paths to reduce ammonia (NH₃) emission in protected spinach and cucumber plots, a field experiment was conducted on the dynamics of ammonia emission fluxes under treatments of biochar addition and ploughing cultivation using aeration method. The results showed that NH₃ emissions mainly occurred within one week after fertilization in both spinach and cucumber plots. Under the condition of 300 kg/hm² of total inorganic nitrogen input, the proportion of NH₃ emission in the total nitrogen input was 8.00% under non-additional biochar treatment, and 10.15% under biochar addition treatments from spinach field, respectively. NH₃ emission after surface fertilization with ploughing cultivation was reduced by 38.34% under the treatments of non-additional biochar, and by 56.22% under the treatments of biochar addition, respectively. Under the condition of 600 kg/hm² of total nitrogen input rate, the proportion of NH₃ emission in the total nitrogen input was 3.03% under the non-additional biochar treatment, and 4.80% under the treatments of biochar addition from cucumber field, respectively. NH₃ emissions after surface fertilization with ploughing cultivation was reduced by 9.45% under the treatments of non-biochar addition, and 37.61% under the treatments of biochar addition, respectively. Surface-applied biochar has positive effect on NH₃ emission in vegetable soils. NH₃ emissions per unit yield after biochar addition were increased by 52.58% for spinach and by 78.17% for cucumber, respectively. According to the characteristics of NH₃ emission and the mitigation effect, it is suggested to reduce the base fertilizer input to control NH₃ emission from protected soils, and perform ploughing cultivation after biochar addition to eliminate the promoting effect on NH₃ emission.