Objective To investigate the effects of overexpression of CRELD1 gene on heart valve-related matrix proteins. Methods CRELD1 gene was obtained by PCR. Target gene eukaryote expression vectors were constructed by pcDNA3.1 (-) vector plasmid, and were identified by restriction enzyme digestion and DNA sequence analysis. Recombinant plasmid was transfected into human embryonic lung fibroblasts （HFL-I）with lipofectamine 2000 (recombinant plasmid group), and HFL-I cells transfected with empty vectors and those without transfection were served as transfection control group and blank control group respectively. Real-Time PCR and Western blotting were employed to detect the relative expression of mRNA and protein of heart valve-related matrix proteins Tenascin-C and Aggrecan in each group. Results DNA sequence of recombinant plasmid agreed very well with that in GenBank according to DNA sequence analysis. The relative expression of Aggrecan mRNA and protein in recombinant plasmid group was significantly lower than that in transfection control group and blank control group (P＜0.05), while there was no significant difference in the expression of Tenascin-C mRNA and protein among groups (P>0.05). Conclusion CRELD1 gene overexpression can decrease the heart valve-related matrix protein Aggrecan in human embryonic lung fibroblasts, which serves as a theoretical framework to demonstrate the roles of CRELD1 gene on atrioventricular septal defect.