木棉科约有20-30属，180-250余种，广泛分布于全球热带地区，以美洲种类最多，中国有5属，6种，分布在云南、广东和广西各地。

木棉科植物皆为落叶乔木，树干粗壮，最高如爪哇木棉（Ceiba pentandra）可高达70米 ；叶互生，单叶或为指状复叶；花两性，大型，辐射对称，单生或聚生；花萼杯状，花瓣伸长，覆瓦状排列；果实为蒴果，种子有绵毛。

许多品种的木材有经济价值，有的可以提取纤维，如木棉（Kapok）；南美轻木（Ochroma lagopus）是世界上最轻的木材；榴莲（Durian），马来亚的著名水果；猴面包树（Bao-bab），在非洲和澳洲干旱地区的品种，树干中贮藏大量水分。1981年的克朗奎斯特分类法将本科放到锦葵目中，1998年根据基因亲缘关系分类的APG 分类法和2003年经过修订的APG II 分类法将本科合并到锦葵科中，列为木棉亚科。

Bombacaceae were long recognised as a family of flowering plants or Angiospermae. The family name was based on the type genus Bombax. As is true for many botanical names, circumscription and status of the taxon has varied with taxonomic point of view, and currently the preference is to transfer most of the erstwhile family Bombacaceae to the subfamily Bombacoideae within the family Malvaceae in the order Malvales. The rest of the family were transferred to other taxa, notably the new family Durionaceae. Irrespective of current taxonomic status, many of the species originally included in the Bombacaceae are of considerable ecological, historical, horticultural, and economic importance, such as balsa, kapok, baobab and durian.