With the rapid development of intelligent connected technologies and autonomous driving, the emerging autonomous modular buses have attracted significant attention in the public transportation field. The autonomous modular buses can achieve flexible design of bus capacity through freely coupling/decoupling vehicles adapting to the uneven distribution of passenger demand in terms of space and time. However, the existing full-route service mode fails to fully leverage the flexible operational characteristics of modular buses to efficiently meet passengers' differentiated needs. Therefore, this study proposed a new service mode for autonomous modular buses, which combined the coupling/decoupling characteristics of modular buses with the differentiated service advantages of the skip-stop strategy to realize efficient and differentiated bus line supply. This paper first employed a discrete-time modeling approach combined with the extended Newell’s theory to develop an optimization model for autonomous modular bus skip-stop services, aiming to minimize passenger travel costs and operator costs. The model simultaneously optimized departure intervals, vehicle groupings, and skip-stop schedules.Firstly, this study adopts a discrete-time modeling method and an extended Newell theory to develop an optimization model for autonomous modular bus skip-stop service mode, with the optimization objectives of minimizing passenger travel costs and operational costs for the agency. It can simultaneously optimize bus headways, vehicle formulation, and skip-stop plans. By extending the Newell theory, the model expands from calculating passenger waiting and travel times at individual bus stops to efficiently calculating these times from the entire bus line system perspective, significantly reducing the modeling complexity. Secondly, taking Bus Route 110 in Dandong as a case study, an optimized operational scheme was proposed and compared under both off-peak and peak periods with the traditional fixed-capacity bus service model and the full-route modular bus service model. The results show that the proposed modular bus skip-stop service mode can greatly reduces the total system cost, saving 3.34% to 24.65%. Specifically, passenger waiting time costs and travel time costs are reduced by 7.49% to 48.52% and 2.31% to 6.28%, respectively. Moreover, during peak hours, modular bus dispatching is more frequent than during off-peak periods, with a tendency to adopt low-capacity vehicle groupings and skip-stop service strategies.