By exploiting vehicle-to-vehicle (V2V) communication in vehicular platoon system, the platoon members could receive the real-time vehicle dynamics information of the leader vehicle and the preceding vehicle, which can be utilized to control the vehicles’ acceleration. However, the interference and the channel uncertainty of V2V communication can impair the communication delay, which deteriorate the vehicle’s ability to maintain the desired velocity and the inter-vehicle distance. This paper performs a joint communication and control analysis of a platoon with the modified cooperative adaptive cruise control (mCACC) scheme. Specifically, the delay requirement to ensure the stability of the platoon control system is derived in the mCACC scheme. Then, the communication delay of the V2V communication links is analytically investigated by combining stochastic geometry and queuing theory. Subsequently, a reliability of the platoon communication system is obtained, which reveals the probability that the V2V communication delay can satisfy the delay requirement of the control system for maintaining the platoon stability. Simulation results validate the theoretical results and present the impact of the critical parameters on the platoon performance.