When the coronavirus disease 2019 (COVID-19) began to ravage the world in 2019, the World Health Organization became concerned. The epidemic has a high mortality and contagion rate, with severe health and psychological impacts on frontline emergency medical service system practitioners. There are many hospital staff surveys, but few have covered the stress among emergency medical technicians. DASS-21, PSQI, and AUDIT questionnaires were used to evaluate the sources of psychological stress factors of firefighters in Taiwan. Multiple logistic regression was used to analyze the questionnaire content. We conducted questionnaire surveys from May 2022 to July 2022. Our sample comprised 688 participants. The odds ratios of increased depression, anxiety, and stress levels due to reduced family or peer understanding and support were 2.72 (95% CI: 1.50–4.92), p = 0.001; 2.03 (95% CI: 1.11–3.68), p = 0.021; and 3.27 (95% CI: 1.83–5.86), p < 0.001, respectively. The odds ratios of poor sleep quality due to depression, anxiety, and increased stress levels were 5.04 (3.18–7.99), p < 0.001; 2.44 (95% CI: 1.57–3.81), p < 0.001; and 4.34 (95% CI: 2.76–6.82), p-value < 0.001, respectively. During the COVID-19 pandemic, poor sleep quality and a lack of understanding and support from the Taiwan firefighting agency staff, family, or peers resulted in increased depression, anxiety, and stress levels.