ABSTRACT Understanding the string stability of connected and autonomous (CA) vehicles is important for evaluating dynamics of regular-CA mixed vehicular flow. Although previous studies proposed CA car-following models and analysed the stability of the model itself, they do not focus on the stability of the regular-CA mixed flow. Additionally, stability analysis methods for traditional car-truck mixed flow cannot be directly applied into CA traffic systems, where the CA vehicle monitors multiple preceding vehicles in the platoon. This study presents a framework that analytically derives the generalized string stability criterion of regular-CA platoons. Moreover, an example is conducted to validate the availability of this analytical framework by using concrete car-following models. Simulation based approaches are also utilized for fully capturing car-following dynamics of vehicular flow. This contribution is helpful for guiding analytical investigation of string stability of regular-CA mixed vehicular flow, thereby giving suggestions for CA design for obtaining optimal stability situation.