As a key enzyme of heme degradation, heme oxygenase (HO) is essential in phytochrome chromophore synthesis, cell protection and stomatal regulation in higher plants. The activity or transcript of HO has been detected in many plant species. Arabidopsis HO1 (HY1), the first map-based cloning gene, could catalyze the transition of heme to carbon monoxide (CO) in vivo. In this review, we first describe HO1 is evolutionarily conserved through comparative analysis of different plants HO1 proteins. Then, we highlight the role of HO1 involved in plants responses to various abiotic stresses such as salinity, drought, cadmium, mercury, ultraviolet radiation, reactive oxygen species, abscisic acid, and hematin. Based on the relationship analysis between nitric oxide, CO, and hydrogen peroxide, we proposed HO1 may be a central repeater for cross talk among them in plants.