In this study, the difference amongst bidders is modelled by the two parameters of valuation and marginal utility. Thus, the symmetrical multi‐unit auction is extended to the asymmetric private value model. The optimal strategy of any different bidders can be solved by the model, which expands the practical application of multi‐unit auction theory. On this basis, the yield and price volatility of different auction mechanisms under the ‘two‐group case’ are evaluated. The results show that Vickrey auction is generally superior to uniform price auction. Different from the other two formats, the fluctuation range of discriminatory price auction revenue is large.