The virtual power plant can effectively solve the problem of the lack of effective coordination and control among independent, multiple small and micro entities. As electricity reform has entered a more different phase in China, virtual power plants are gradually participating in market competition as comprehensive e-commerce vendors. Starting from the retail market, this paper proposes a two-stage double-layer random bidding strategy model in which virtual power plants participating in the spot joint market. In the first stage, based on the output characteristics of multiple small and micro entities such as distributed energy, power users, and distributed energy storage, a virtual power plant model that aggregates multiple small and micro entities is constructed. In the second stage, based on the Stackelberg leader-follower game, a dual-layer model of joint bidding strategy in the spot market is proposed, which takes virtual power plants as the bidding body and takes into account both income and risk. The upper level makes strategic quotations with the goal of maximizing the revenue of the virtual power plant; the lower level makes a joint day-ahead clearing of the multi-level market with the goal of minimizing power purchase costs. In addition, multi-scenarios are introduced to describe the risks brought by the uncertainty of competitors to the benefits of virtual power plants during the transaction decision-making game. The analysis of the example verifies the feasibility and effectiveness of the proposed model.