Objective To investigate the relationship between ultrasonography score and clinical severity in elderly patients with acute cholecystitis, and acquire a quantifiable index of disease severity to provide reference for therapy. Methods According to clinical manifestation, 72 elderly acute cholecystitis cases were classified into mild, moderate and severe cases. These cases were scored based on pre-surgery ultrasonic image index (enlarged gallbladder, thickened gallbladder wall, double-layer image, gallbladder stones, incarcerated gall-stone, echo in gallbladder fluid, peri-gallbladder effusion or adherence), prediction and pre-surgery guidance value of which for severity of acute cholecystitis were evaluated. Results Of 72 cases, there were 36 mild cases, 21 moderate cases and 15 severe cases. The cases showing enlarged gallbladder, thickened gallbladder wall, double-layer image, gallbladder stones, incarcerated gall-stone, echo in gallbladder fluid, peri-gallbladder effusion or adherence were mostly moderate cases and severe cases with statistical significance compared with mild cases(P＜0.05). Twenty-eight cases with score ≤5 were mainly consisted of mild cases, which accounted for 92.9% (26/28). The cases with score 6-9 were mainly consisted of moderate cases, which accounted for 57.7% (15/26). The cases with score ≥10 were mainly consisted of severe cases, which accounted for 72.2% (13/18). It was shown that ultrasonography scores highly coincided with intra-surgery findings. There were significant differences among three groups in the number of cholecystostomy cases (P＜0.05). Conclusion Ultrasonography score could provide quantifiable index for clinical severity of acute cholecystitis in the elderly and has guidance value for clinical therapy. Ultrasonography score might be used as a reference for surgery intervention timing.