A hybrid slot MAC protocol based on reservation mechanism for multi-density ad hoc network, short for RTV, is presented in this paper. The service is distinguished into the reservation and the contention-free in RTV for providing different qualities of access transportation service. The variable delay reservation algorithm is adapted to support different time-delay services, which solves the problem that TDMA isn't applicable to the multi-density network. The throughputs and slot-utilization rate of the RTV are obtained. The simulation results indicate that the RTV presents good performance on throughputs and slot-utilization rate in large multi-density network.