Thermal insulations have begun to play an increasing important role in realizing building energy saving in the past years. Thermal insulations made of biomasses like agro-residues, forest residues, etc., are developing very fast recently, although their research and development history is relatively short. In order to help researchers to achieve a global viewpoint of the research on this topic and to improve the research and application progress, a systematic review is presented in this study. After review and screening, 144 original research journal papers were selected as samples and analyzed to investigate the following topics: Historical development of bio-insulations from 1974 up to April 2016, from viewpoint of number of papers published and corresponding journals; Geographical distribution of researchers, according to country and continent categories; Kinds of biomasses under research including agro-residues, forestry residues, economic plants, etc.; Analysis methodologies and research scale of bio-insulations; Common types, manufacturing methods and properties of bio-insulation; Experimental equipment, software, and corresponding standards. Moreover, the shortcomings of the current research are discussed in details. Finally, some suggestions are presented, including: a scientific plan on bio-insulation research; selection of suitable types; traditional and innovative treatments for improving specific properties; the required properties testing order; scientific presentation of research results. This study can help to achieve a more precise comprehension about bio-insulations research status, find suitable experimental equipment for effectively testing various properties, adopt innovative ways to improve specific properties, avoid making mistakes during the research and provide a better expression of the research results. Furthermore, this study can stimulate the research and application of bio-insulations to get a great-leap-forward development in the near future, especially in the fabricated building field. 1. Background and introduction Nowadays, industry, transportation and buildings are the three major social energy consumers. In particular, with the increasing demand of indoor thermal comfort, more and more energy is consumed in the building sector by the energy systems providing heating, ventilation, and air conditioning services. The improvement of the thermal insulatio n of buildings is one of the most effective ways to get energy savings, through the reduction of heat or cold losses through envelopes. However, many traditional construction materials do not have good thermal insulation properties. So, many kinds of extra thermal insulation materials, like solid boards (panels), solid bucks, particles, sandwiches, coils are being used in many parts of the buildings, such as in the exterior walls, roofs, floors and exterior doors. These materials can be applied not only in traditional buildings but also in fabricated buildings. The common insulations can be classified into four categories depending on the raw material: (1) from rocks and slags, such as rock-wool, glass-wool, expanded perlite, glass beads, vermiculite, cinder, ceramic products, etc.; (2) from petrochemical and coal chemical intermediate products, such as Polystyrene, Polyurethane, Polyethylene, etc.; (3) from plants, including agricultural waste, forestry waste and industrial plants fiber waste, such as straws, rice husk, waste papers, wood shavings, cotton, corn crops, etc.; (4) from metals, such as metal reflection film, hard metal visor, radiation plate, etc., the applications of which are still limited because they can only be applied in roofs and they are much more expensive than other thermal insulation materials. Jelle  summarized the state of traditional thermal building insula-http://dx.