Objective To study the preparation method of acellular vascular matrix and to evaluate its biocompatibil ity and safety so as to afford an ideal scaffold for tissue engineered blood vessel. Methods Fresh caprine carotids (length, 50 mm) were harvested and treated with repeated frozen (—80 )/thawing (37℃), cold isostatic pressing (506 MPa, 4 ), and 0.125% sodium dodecyl sulfate separately for preparation of acellular vascular matrix. Fluorescence staining and DNA remain test were used to assess the cell extracting results. Biological characteristics were compared with the raw caprine carotids using HE staining, Masson staining, scanning electron microscope (SEM), and mechanical test. Biocompatibil ity wasdetected using cell adhesion test, MTT assay, and subcutaneously embedding test. Ten SD rats were divided into 2 groups (n=5). In experimental group, acellular vascular matrix preserved by the combination of repeated frozen/thawing, ultrahigh pressure treatment and chemical detergent was subcutaneously embedded; and in control group, acellular vascular matrix preserved only by repeated frozen/thawing and ultrahigh pressure treatment was subcutaneously embedded. Results HE staining and Masson staining revealed that no nucleus was detected in the acellular vascular matrix. SEM demonstrated that a lot of collagen fibers were preserved which were beneficial for cell adhesion. Fluorescence staining and DNA remain test showed that the cells were removed completely. There was no significant difference in stress and strain under the maximum load between before and after treatment. Mechanical test revealed that the acellular vascular matrix reserved mechanical properties of the raw caprine carotids. Cell adhesion test and MTT assay confirmed that cytotoxicity was grade 0-1, and the acellular vascular matrix had good compatibil ity to endothel ial cells. After subcutaneously embedding for 8 weeks, negl igible lymphocyte infiltration was observed in experimental group but obvious lymphocyte infiltration in control group. Conclusion The acellular vascular matrix, which is well-preserved by the combination of repeated frozen/thawing, ultrahigh pressure treatment, and chemical detergent, is an ideal scaffold for tissue engineered blood vessel.