Biological safety cabinet

The invention belongs to the technical field of experimental equipment, and particularly relates to a biological safety cabinet. The invention aims to solve the problems that the biological safety cabinet can meet the single experiment requirement, and multiple types of biological safety cabinets need to be configured. According to the biological safety cabinet, part of gas in the working area enters the circulating air duct through the air inlet and enters the working area again through the air supply outlet to be recycled, and therefore power consumption can be reduced. And the other part of air in the working area enters the exhaust air duct through the air suction port and is exhausted through the indoor air outlet or the outdoor air outlet. When air is exhausted from an outdoor air outlet, the device is suitable for experiments of harmful chemical gas, chemical volatile gas and the like. When air is exhausted from the indoor air outlet, the cleanliness of the air in the first workbench area is improved,