Objective To investigate the current status, clinical antimicrobial use, and antimicrobial resistance of hospitalized patients due to lower respiratory tract (LRT) infection with Pseudomonas aeruginosa (PA), so as to provide reference for clinical treatment. Methods Medical records of hospitalized patients with LRT PA infection from January 2021 to November 2022 in a hospital were collected retrospectively. Basic characteristics, infection status, treatment department, infection site, clinical medication, and antimicrobial susceptibility test results of patients were analyzed statistically. Results A total of 91 patients were selected, out of which 64 patients (70.33%) were ≥80 years old and 72 (79.12%) cases had healthcare-associated infection. Besides PA, the most commonly detected strains were Klebsiella pneumoniae (17.98%), followed by Acinetobacter baumannii (16.23%) and Streptococcus viridans (14.47%). Cefoperazone/sulbactam, piperacillin/tazobactam and meropenem were the most frequently used antimicrobial agents treating LRT PA infection, accounting for 67.03%, 58.24%, and 58.24%, respectively. After using imipenem and meropenem, resistance rates of PA to both antimicrobials increased from 32.69% and 40.38% to 69.23% and 63.46%, respectively. Conclusion Continuous use of antimicrobial agents is associated with the rapid development of resistance in PA. It is particularly important to adjust treatment plans timely based on patient clinical indications and antimicrobial susceptibility test results.