Objective To study the expression pattern of brain natriuretic peptide （BNP） in myocardial tissue from forensic routine cases and to explore its application value in the forensic determination of sudden cardiac death （SCD）. Methods The data of 96 autopsy cases accepted by the center of Medico-legal Investigation of China Medical University between December 2008 to May 2014 were collected. There were 62 cases in SCD group cardiac and 34 cases in non-SCD group. The myocardial tissues were taken from left and right ventricular wall, respectively. The expressions of BNP protein and BNP mRNA in myocardial tissue were detected by HE staining, immunohistochemical staining, Western blotting and quantitative real-time reverse transcription-polymerase chain reaction （RT-qPCR）, etc. Results The immunohistochemical staining of myocardial tissue showed diffusely positive staining in SCD group, and patchily or diffusely positive staining in non-SCD group with lighter degree. The result of Western blotting showed that the expression of BNP protein elevated in left ventricular wall of SCD group. The result of RT-qPCR showed a positive correlation between the BNP mRNA expressions in bilateral ventricular walls and the heart weight, bilateral lung weight, and N-terminal prohormone of brain natriuretic peptide （NT-proBNP） concentration. There were large differences between the BNP mRNA concentrations in SCD group and non-SCD group, and the former was statistically higher （P<0.05）. Conclusion The expressions of BNP protein and BNP mRNA in myocardial tissue are related to the causes of death. Combined with pathological changes, the expressions of BNP protein and BNP mRNA in myocardial tissue have certainly practical significance for the determination of SCD and the analysis of the death mechanism in the cases related to forensic pathology.