Objective To explore the inhibitory effect of various concentrations of low molecular weight heparin on the formation of catheter-related thrombosis ( CRT). Methods Forty rabbits were divided into group A ( control group), group B (low concentration low molecular weight heparin group), group C (medium concentration low molecular weight heparin group), and group D (high concentration low molecular weight heparin group) in accordance with a random number table. After successfully establishing the PICC catheterized rabbit model, a 0. 9% sodium chloride solution, or 50 μ/ (mL·d), 100 μ/ (mL·d), or 200 μ/ (mL·d) low molecular weight heparin sodium solutions were applied. The solution was injected subcutaneously into the abdomen of the rabbits once a day for 7 consecutive days. The auricular vein,anterior vena cava, and PICC catheters of the rabbits were removed for HE staining, and the incidence of CRT and coagulation functions in different parts were observed and compared under a light microscope. Results The incidence of CRT in group A was 100% and there was no thrombosis in group D. The difference in the incidence of thrombus between group A and the other three groups was statistically significant ( P < 0. 01). The incidences of rabbit auricular vein thrombosis in groups A-C were significantly different from that of group D (P<0. 01). The incidences of PICC catheter thrombosis in groups A and B were significantly different from that in groups C and D (P<0. 01). One week after PICC insertion, blood PT, APTT, TT, FIB, and D-D dimer levels were significantly different among the groups (P< 0. 01). Conclusions Different concentrations of low molecular weight heparin have a preventive effect on the formation of CRT. A high concentration low molecular weight heparin 200 μ/ (mL·d) effectively prevents the formation of CRT and reduces its incidence, which has important clinical significance.