To cater for the scenario of coordinated transportation of multiple trucks on the highway,a platoon system for autonomous driving has been extensively explored in the industry.Before such a platoon is deployed,it is necessary to ensure the safety of its driving behavior,whereby each vehicle\'s behavior is commanded by the decision-making function whose decision is based on the observed driving scenario.However,there is currently a lack of verification methods to ensure the reliability of the scenario-based decision-making process in the platoon system.In this paper,we focus on the platoon driving scenario,whereby the platoon is composed of intelligent heavy trucks driving on cross-sea highways.We propose a formal modeling and verification approach to provide safety assurance for platoon vehicles\'cooperative driving behaviors.The existing Multi-Lane Spatial Logic(MLSL) with a dedicated abstract model can express driving scene spatial properties and prove the safety of multi-lane traffic maneuvers under the single-vehicle perspective.To cater for the platoon system\'s multi-vehicle perspective,we modify the existing abstract model and propose a Multi-Agent Spatial Logic(MASL) that extends MLSL by relative orientation and multi-agent observation.We then utilize a timed automata type supporting MASL formulas to model vehicles\'decision controllers for platoon driving.Taking the behavior of a human-driven vehicle(HDV) joining the platoon as a case study,we have implemented the model and verified safety properties on the UPPAAL tool to illustrate the viability of our framework.