To investigate the correlation between the expressions levels of serum brain natriuretic peptide (BNP) and procollagen type III N-terminal peptide (PIIINP) of the pregnant women with preeclampsia and their cardiac function. Methods: A total of 62 pregnant women with preeclampsia were selected in group A, 78 pregnant women with pregnancy induced hypertension were selected in group B, and 80 healthy pregnant women were selected in group C from December 2018 to October 2020. The general data of the women in the three groups were collected. The cardiac uhrasonography indexes, such as left ventricular ejection fraction (LVEF), cardiac index (CI), cardiac output (CO), early diastolic peak velocity (E), late diastolic peak velocity (A), and E/A of the women in the three groups were measured by color Doppler ultrasound. The levels of serum BNP and PIIINP were detected by enzymelinked immunosorbent assay (ELISA). The correlation between serum BNP and PIIINP levels of the women with preeclampsia and their cardiac function was analyzed by Pearson method. Results: The levels of BNP and PIIINP, and the values of A, CO, and TG of the women in group C, group B, and group A had increased in turn, while the values of E, E/A, LVEF and CI of the women in group C, group B, and group A had decreased in turn (all P＜0.05). There was positive correlation between the serum BNP level of the women with preeclampsia and their serum PIIINP level. The levels of serum BNP and PIIINP of the women with preeclampsia were positively correlated with their values of A and CO, but which were negatively correlated with their values of E, E/A, LVEF, and CI (all P＜0.05). Conclusion: The serum BNP and PIIINP levels of the women with preeclampsia were significantly correlated with their echocardiographic parameters. The serum BNP and PIIINP levels combined with echocardiography examination can judge the development of preeclampsia timely in clinic.