Atomic absorption spectrometry (AAS) is widely used in the analysis and detection of heavy metals. The optimal operation conditions on metals detection are important for the stabilization and repeatability of scientific research, which affects the expected investigation objectives greatly. Thus, it becomes a key issue to establish appropriate detection methods in scientific works. Calendula officinalis was used for lead/cadmium remediation in contaminated loess, and the flame atomic absorption spectrometry (FAAS) with wet digestion was applied to analyze the contents of lead/cadmium in Calendula officinalis seedlings. The investigation data was further studied to reveal the bioaccumulation efficiency of lead/cadmium in Calendula officinalis seedlings. The results showed: the limits of detection are 0.104 and 0.007 mg·L-1 for lead and cadmium; the recovery rates of lead and cadmium are from 94.33% to 110.78% and 97.73% to 107.50% respectively. The relative standard deviations (RSD) are between 4.11% and 4.75% for lead while between 1.11% and 2.77% for cadmium, and It’s been proved that the method is accurate and reliable. The low accumulation efficiency of lead with Calendula officinalis seedlings might be related to the electronegativity of lead while the growth period of calendula officinalis seedlings and environmental factors. The accumulation content of cadmium is 104.85 mg·kg-1 with cadmium concentration of 50 mg·kg-1. The co-existing of lead in loess is positive for cadmium accumulation by Calendula officinalis seedlings, and the synergistic effect might work in the process. The established detection method is effective for quantitative analysis of lead and cadmium in calendula officinalis seedlings and significant for future research.