Phytohormone is a kind of trace organic substance which is synthesized by plant. The main function of plant hormone lies in regulation to the growth, development and acclimation to the environments. Algae belong to the lower plant group and have similar kinds of phytohormones. Compared to the terrestrial plant, the content of phytohormone in the algae is less than that in higher plant. The investigation regarding to stress responding is always active no matter in higher plant or algae. As a stress responding hormone, the function of abscisic acid has been recognized widely. Here, we summarized the progress in the identification of ABA in algae, signal transduction mechanism of stress responding mediated by ABA, and evolution analysis based on the protein structure and translation patterns. Then, we suggested that the study regarding to the stress responding in algae should focused on the mechanisms in the intertidal algae.