Objective Exploring the evaluation value of left ventricular myocardial layered strain and peak strain dispersion (PSD) on left ventricular function in patients with left heart failure (LHF) and its correlation with brain natriuretic peptide (BNP).Methods 123 patients with LHF admitted to our hospital between May 2023 and April 2024 were selected as the study subjects. They were divided into grade II and grade III groups according to the New York Heart Association (NYHA) classification. Two spot tracking imaging and serological testing were performed on them, and their left ventricular conventional ultrasound parameters, myocardial stratified strain (GLSendo, GLSmid, GLSepi) parameters, PSD parameters, and serum BNP levels were analyzed. Pearson correlation coefficients were used to analyze the correlation between GLSendo, GLSmid, GLSepi, PSD, and BNP; Use receiver operating characteristic (ROC) curves to evaluate the diagnostic efficacy of GLSendo, GLSmid, GLSepi, PSD, and BNP for left ventricular function in LHF.Results There was no significant difference in left ventricular end diastolic volume (LVEDV), left ventricular end systolic volume (LVESV), left ventricular posterior wall thickness (LVPWT), left ventricular ejection fraction (LVEF), mitral valve flow spectrum E/A value, and left ventricular mass index (LVMI) between the two groups (P>0.05). The levels of GLSendo, GLSmid, and GLSepi in the Grade III group were lower than those in the Grade II group, while PSD and BNP were higher than those in the Grade II group (P<0.05). Pearson correlation analysis showed that GLSendo, GLSmid, GLSepi were negatively correlated with BNP, while PSD was positively correlated with BNP (P<0.05). ROC analysis showed that the diagnostic ACU values of GLSendo, GLSmid, GLSepi, PSD, BNP, and combined detection for left ventricular function in LHF were 0.847, 0.822, 0.874, 0.830, 0.867, and 0.998, respectively, which were significantly different from Az=0.5 (P<0.05).Conclusion There is a significant correlation between left ventricular myocardial stratified strain and fractional strain dispersion with BNP, which can effectively evaluate left ventricular function in patients with left heart failure.