Vehicular ad hoc networks (VANETs) provide the related techniques and solutions for intelligent transportation, urban planning, pollution reduction and other issues. VANET applications usually require vehicle users to report continuous road location information, which brings a serious threat to personal trajectory privacy. However, the existing trajectory protection techniques are mainly focused on location-based protection, which cannot be applied to road segment based trajectory privacy protection effectively. In this paper, we propose a new road segment data gathering framework with trajectory privacy protection consideration in VANETs. In our framework, we give the trajectory privacy protection definition, formulate the problem model of road segment based data report, and prove that the problem is a NP-hard problem. In addition, we also present approximated algorithms to solve the problem. The experimental results show that our algorithms have good performance in both user's trajectory protection and coverage rate of data gathering.