The present invention relates to a method for preparing, activating and regenerating a metal supported catalyst, comprising: treating a M.sub.a-M.sub.b-M.sub.c metal supported catalyst at 10-700 C. by using an ammonia or nitrogen-containing organic matter, wherein the M.sub.a metal is an active metal selected from one or more of a noble metal atom or a transition metal, the support is a common industrial porous catalyst, and the M.sub.a metal is dispersed on the support in a state of single atomic site. According to the M.sub.a-M.sub.b-M.sub.c metal supported noble metal/zinc catalyst treated by the method of the present invention, the direct dehydrogenation conversion rate and selectivity of catalyzing light alkanes are remarkably improved; the method for preparing the catalyst is simple in process, the catalytic activity after regeneration is still kept, and the catalyst can be industrially produced on a large scale.