The invention discloses an adjustable fixing device with a protective structure. The adjustable fixing device comprises a fixing support. A fixing block is installed on the fixing support, an installing base is installed on the fixing block, and protective covers and protective belts are oppositely installed on the upper end face of the installing base, wherein the protective belts are located on the inner sides of the protective covers. The adjustable fixing device is adjustable in space position, multi-angle installing and fixing of a camera, a motor and other devices through the fixing device can be well achieved, and adjusting of the space position is conveniently achieved; a protective device for the device is designed, and damage, caused by accidents, to the device is effectively avoided; in the structural design aspect, the fixing device is formed in the mode that low-cost common sheet metal, low-cost common steel tubes and the like are stamped and welded, the design size is high in flexibility, most parts can be made of leftover materials, cost is low, practicability is high, and the adjustable fixing device is firm and durable.