A regular floor fan, as shown in FIG. 1, generally comprises a fan head 1′, a support shank 2′ and a base 3′, which sequentially connected with each other. The support shank 2′ is retractable, so the upright height of the fan head 1′ is adjustable by raising the support shank 2′ up or drawing it down. However, the adjustable range of height of the fan head 1′ is restricted, because the retractable length of the support shank 2′ is limited, such an electric fan can be arranged into a floor fan only, and can not be arranged into a desk fan. Moreover, the fan head 1′, the support shank 2′ and the base 3′ need to be detached during package and transportation, and the user has to reassemble them together before using. The process of detachment is time-consuming, and the operation is complicated. A risk of losing some tiny parts may also exist. Further, influenced by the size of the base which is usually a regular disc-like base and the length of the support shank, the electric fan after detachment also occupies a large space even if it can be detached into several parts and packed up separately. Thus, the cost of package and transportation is greatly increased.