Objective To investigate the efficacy of low-molecular-weight heparin calcium combined with physical therapy in the prevention of deep venous thrombosis (DVT) of lower limbs in elderly patients who have been staying in bed for long periods. Methods A total of 119 long-term bedridden elderly patients admitted to Beijing Rehabilitation Hospital from November 2019 to October 2022 were subjected and then randomly divided into control group (59 cases, low-molecular-weight heparin calcium) and the combination group (60 cases, low-molecular-weight heparin calcium combined with physical therapy). Their blood coagulation indicators, hemorrheological parameters, DVT occurrence, and incidence of adverse reactions were observed and compared between the two groups. SPSS statistics 23.0 was used for statistical analysis. Data comparison between two groups was performed using student′s t test or Chi-square test depending on data type. Results After treatment, the combined group had significantly longer thrombin time and prothrombin time, and lower whole blood high shear viscosity, whole blood low shear viscosity and incidence of DVT when compared with the control group [(14.56±2.60) vs (13.02±2.74) s, (13.75±2.86) vs (12.35±2.530 s, (4.66±0.52) vs (5.10±0.87) mPs·s, (10.89±1.43) vs (11.78±1.90) mPs·s, 0 (0.00%) vs 7 (11.86%); P<0.05]. There were no statistical differences in activated partial thromboplastin time, plasma viscosity and incidence of adverse reactions between two groups. Conclusion Combination of low-molecular-weight heparin calcium and physical therapy can improve the blood coagulation status to a certain extent, and reduce the blood viscosity and incidence of DVT in long-term bedridden elderly patients.