Fundamentally, traveling on highways is bought by road users who deserve quick and satisfactory ser- vice. Currently, highway toll gates are generally congested. In view of this situation, this paper, by taking a toll station in Jiangsu province according to regulations of Jiangsu provincial highways as an example, and by using relevant theories of toll gate design as well queuing theory, introduces the current calculation method of the free passing lane. Aiming at current shortcomings, this paper also presents the lane length conversion and lane area conversion optimization model. Meanwhile, it increases the queue length value parameter as an important part of the optimization and improvement model. Then, the queue length values are used to theoretically verify the cal- culations. The research results show that the results obtained are accurate and reasonable by using the optimiza- tion model, which can greatly reduce civil disputes caused by free clearance. The verification of the length of the queuing system has given theoretical support to the laws and regulations on free passing position.