The high risk and asymmetric information in venture investment make the allocation of control rights in venture firms a key to the success of that venture investment. Unlike previous studies, this paper defines the control right as the discrete variables in the zone of [0, 1]. In order to correctly evaluate investment opportunities and reasonably display the characteristics of phased investment, this paper analyzes the value of venture firms by using real options for different control rights allocation tactics. Regarded firm value as a restraint conditions, a decision-making model is established for quantative study on relationships between venture firm value and allocation of control rights. This paper not only provides the basis for venture capitalists and entrepreneurs to allocate control rights at venture firms and make decisions on investment, but also put forwards an evaluating method for venture firm value under different control rights allocation tactics. Computational experience demonstrates the solution process of the control rights allocation model presented in this paper.