Pyogenic liver abscess (PLA), a very uncommon liver disease in the normal pediatric group is often associated with immunocompromised conditions. Pseudomonas aeruginosa has long been regarded as a relatively rare pathogen of PLA, especially in patients without underlying problems. A previously healthy one-year-and-seven-month-old boy who had symptoms of fever, vomiting and diarrhea got a liver abscess at right hepatic lobe which was confirmed by abdominal ultrasound and computed tomography (CT) diagnoses. Ultrasound-guided percutaneous aspiration of liver abscess was done soon after the confirmation. The culture result of aspirate grew P. aeruginosa. The patient received a 4-week course of adequate antibiotics treatment after the aforementioned aspiration procedure. In addition, a series of ultrasounds were performed to follow the resolution of abscess during the treatment period. The immune function tests of the patient were within normal ranges. Finally, the lesion resolved completely without leaving any complication.