Bleaching powder is a mixture of calcium hydroxide, calcium chloride and calcium hypochlorite. The main component is calcium hypochlorite, and the content of available chlorine is 30%-38%. Bleaching powder is white or white-like powder or particles, with obvious chlorine smell, instability and strong hygroscopicity.

Bleaching powder is easily decomposed by light, heat, water and ethanol. Bleaching powder is dissolved in water, and its aqueous solution can turn litmus paper blue, and then gradually fade and turn white. Hypochloric acid will be released when it meets carbon dioxide in the air, and it will produce a lot of chlorine when it meets dilute hydrochloric acid.