The invention relates to algal symbiotic bacteria for producing phloroglucinol and a method to produce the phloroglucinol. The algal symbiotic bacteria are selected from marine wild bacterial strains being capable of producing the phloroglucinol, wherein the marine wild bacterial strains are trained and are modified in resistance gene, thereby producing the phloroglucinol safely and environment-friendly at low energy consumption and high quality. The method avoids high environment pollution and complex and low-quality products in production through chemical methods, and avoids safety hidden risk due to complete transgenosis, and meanwhile, the algal symbiotic bacteria sourced from sea can be cultured with abundant algae as a culture medium, thereby largely reducing production cost.