Objective To explore the predictive value of color Doppler ultrasound combined with shear wave elastography (SWE) parameters for the poor prognosis of patients with decompensated cirrhosis (DCC) over a 12-month period. Methods A total of 86 patients with DCC admitted to Zhengzhou Sixth People’s Hospital from March 2024 to March 2025 were enrolled. All patients underwent abdominal color Doppler ultrasound combined with SWE examination within 72 hours of admission. And the liver morphology, portal vein diameter (PVD), portal vein velocity (PVV), splenic vein diameter (SVD), splenic vein velocity (SVV), liver artery resistance index (RI), and liver stiffness measurement (LSM) were recorded. The follow-up period was 12 months. The patients were divided into the good prognosis group and the poor prognosis group based on the prognosis. Univariate and multivariate Cox regression analyses were performed to screen independent risk factors. The optimal cut-off values of each indicator were determined by maximum Youden index via receiver operator characteristic (ROC) curve, and Kaplan-Meier method with Log-rank test was adopted to compare survival differences. Results Among 86 patients, 32 suffered adverse events within 12 months, with an incidence of 37.21%. The proportion of patients with Child-Pugh C grade liver function and severe ascites in the poor prognosis group was significantly higher than that in the good prognosis group (all P＜0.05). The PVD, SVD, liver artery RI, spleen thickness, and LSM in the poor prognosis group were significantly higher than those in the good prognosis group (all P＜0.05), while PVV and SVV were significantly lower than those in the good prognosis group (all P＜0.05). The ROC curve analysis revealed that the optimal cut-off values: PVD≥1.42 cm, PVV≤ 10.8 cm/s, hepatic artery RI ≥0.71, LSM≥19.5 kPa, with area under the curve (AUC) of all four indicators over 0.75, showing favorable predictive efficacy. After adjusting for confounding factors including Child-Pugh grade of liver function and ascites, multivariate Cox regression verified that all four indicators as independent risk factors for poor prognosis (all HR＞1, P＜0.05). Kaplan-Meier curves revealed significant differences in 12-month survival between groups divided by cut-off values (all P＜0.05). Ultrasound characteristics varied across complications: portal hemodynamic abnormalities dominated bleeding patients, splenomegaly was prominent in ascites patients, while patients with liver failure or death had the highest LSM and hepatic artery RI. Conclusion Color Doppler ultrasound combined with SWE parameters can non-invasively assess the portal hypertension (PH) and fibrosis degree in patients with liver cirrhosis. PVD, PVV, hepatic artery RI, and LSM are all independent indicators for predicting the 12-month poor prognosis of DCC patients, and the critical values can be used for screening and stratification of high-risk clinical populations.