Methyl bromide is a commonly used insecticide and fungicide, which is typically used for the fumigation of farmland soil. Methyl bromide residues not only deplete the ozone layer and affect ecological balance but also contribute to the deterioration of soil quality and changes in the community structure of soil microorganisms, which are sensitive biological indicators of soil health. In order to clarify the effect of methyl bromide on the microbial community structure and ecological processes in farmland soil, we examined soil planted with strawberry in the Hong-gu District of Lanzhou City over two consecutive years, and measured related indicators such as soil microbial biomass carbon, basic respiration, induced respiration, and microbial metabolic entropy. The mechanisms of different microbial groups were determined using the phospholipid fatty acid (PLFA) method. The results indicated that over a culture period of 90 days following methyl bromide fumigation treatment, microbial basal respiration and induced respiration decreased by 0.6% and 16.2%, respectively, which were significantly different from the control values (P < 0.05). At the end of the microbial carbon culture, there was a 5.6% decrease in biomass carbon, which was significantly different from the control value (P < 0.05). Generally, microbial basal respiration, induced respiration, and microbial biomass carbon all showed a trend of gradual recovery after an initial decline, and microbial metabolic entropy (qCO₂) was higher than that of the control on the 15th day. However, the difference between the treatment group and the control group decreased gradually with the prolongation of culture time, although it had still not recovered at the end of the culture period, the difference being 5.1%. Methyl bromide has inhibitory effects on soil bacteria (B), fungi (F), gram-negative bacteria (GN), and gram-positive bacteria (GP). The soil contents of bacteria and fungi decreased by 0.64%-8.72% and 0.03%-5.61% respectively, in response to methyl bromide treatment. By the end of the training period, the amounts of GP and GN had decreased by 0.26% and 10.42%, respectively. The sensitivity of GN to methyl bromide was stronger than that of GP, although the change in GN was delayed. Methyl bromide treatment reduced both B/F and GN/GP ratios, although the effect on the GN/GP ratio was more significant than that on the B/F ratio, and there was an increase in the soil microbial pressure index. In summary, our findings indicate that the application of methyl bromide exerts long-term and persistent exogenous pressure stress on farmland soil microorganisms. Methyl bromide kill harmful microorganisms, and also cause considerable harm to beneficial microorganism, which is unfavorable to the maintenance of favorable soil conditions and decreases the richness and diversity of microorganisms in the soil. Accordingly, the negative effects of methyl bromide on soil microorganisms should be fully considered in practical applications.