Abstract: The pollution of harmful elements has restricted the development and utilization of Sargassum horneri. In order to reduce the content of chromium, arsenic, cadmium and lead in Sargassum horneri, the best remover was selected. The removal process was optimized through single-factor experiments and orthogonal experiments. And high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS) was used to analyze the change of Arsenic species in Sargassum horneri before and after removal, and the optimized process was applied to Hizikia fusifarme and Scagassum. The results showed that with 1.5% EDTA-2Na as the remover, the removal rate of chromium was 71.34% under the process conditions of 1:30 g/mL, 4 h, and 30℃. The removal rate of total arsenic was 66.32%, among which the more toxic As³⁺ and As⁵⁺ was 100% and 91.43%. The removal rate of cadmium was 87.40%, and the removal rate of lead was 87.64%. The content was lower than the national standard limit, and the loss rate of fucoxanthin in the Sargassum horneri was within an acceptable range. The removal rate of harmful elements such as chromium, arsenic, cadmium and lead in the Hizikia fusifarme was 57.27%, 66.00%, 87.14% and 88.88%;The removal rates of harmful elements such as chromium, arsenic, cadmium and lead in Scagassum were 55.56%, 56.89%, 87.14% and 96.44%.The process is simple and easy to operate, which can remove most of the more toxic inorganic arsenic with certain applicability. It provides an idea for industrially reducing the content of harmful elements in seaweed.