The invention discloses a method for preparing a chiral alkyl compound through asymmetric catalytic hydrogenation of an E/Z mixed or single-configuration trisubstituted olefin. The method comprises following steps: taking a trisubstituted olefin represented by formula II as a raw material, taking normal-pressure hydrogen as a hydrogen source, taking a CoBr2-IIP complex as a catalyst, and taking asilane compound as a cocatalyst, reacting for 24-48 hours under the action of a reducing agent. The raw material is the E/Z mixed trisubstituted olefin or a single E or Z configuration trisubstitutedolefin; when E/Z mixed trisubstituted olefins are used, the ratio of E to Z configurations is not limited, the raw materials are easily avaiable, and the cost is saved. The method disclosed by the invention is mild in reaction conditions, simple and convenient to operate, high in atom economy, relatively good in reaction conversion rate which can reach more than 99% generally, and relatively highin enantioselectivity which is 70%-98% generally.