Abstract: Agar is an important marine polysaccharide product. In order to further improve the domestic agar product processing system and the realization of localization of deep processing technology products such as high transparency agar. This paper aimed to explore the preparation of high transparency agar,based on comparing the qualities between domestic agar and imported high transparency agar. With transparency and gel strength as indicators of evaluation,a single factor experiment was performed on the effect of the high transparency agar batching process,the amount of chloroacetic acid added,the reaction temperature,the reaction time,the cleaning pH and the type of raw materials. The results showed that the transparency,turbidity,whiteness and gel strength of the high transparency agar were 92.3%,21.1 NTU,65.61%,801.5 g/cm²,respectively. In comparison,the high transparency agar had higher transparency and whiteness than those of domestic agar,while the turbidity and gel strength were lower than those of domestic agar. The transparency was improved by using the carboxymethylation modification. The optimized reaction conditions were as follows:the agar was added after Na₂SO₄ and other reagents dissolution,followed by addition of 0.38 g/g chloroacetic acid in two portions at intervals of 10 min. The reaction was carried out at 50 ℃ for 50 min. Adjust pH=5.0 after cleaning. The process conditions were stable,and for three different agars,the results showed the transparency,gel strength and turbidity of 96.5%,1095.2 g/cm² and 8.9 NTU,respectively,which meet the counterparts of the high transparency agar. In short,this study develops a process for producing a high-transparency agar,which provides a reference for value-added utilization of agar.