In this paper, we provide several benchmark results for various trajectory-based non-adiabatic simulations on polariton relaxation dynamics. The non-adiabatic methods we use in our benchmark are well-known in the literature, such as MQC-based methods and the recently developed mapping-based methods (both γ-SQC and spinmapping representation). In particular, we showed that the MQC-based methods (MFE and GFSH) are able to qualitatively capture the initial relaxation dynamics of the polaritonic system but are unable to accurately describe subsequent relaxation to the dark states and the lower polariton states. The spin-mapping method that we chose (spin-LSC) markedly improves on the MQCbased methods in terms of simulating the relaxation dynamics of polaritons, although it is unable to capture the correct rates of relaxation from the dark states to the lower polariton state. In comparison with the other three methods, we find that the γ-SQC method is able to accurately capture all relevant relaxation dynamics of the polariton system, including the transition from dark state to lower polariton states at long time scales. Thus, for the models investigated in this work, we see that the γ-SQC method outperforms the other three methods to describe the relevant polariton physics in the HTC model. Despite this observation, more work remains to be done to theoretically investigate the limitations of the other trajectory-based methods and address their shortcomings in terms of simulating the relevant dynamics for polariton chemistry and physics. We further envision that our benchmark results will provide useful information to the emergent polariton chemistry and physics community by showcasing the applicability of various trajectory-based methods to analyze problems of interest, such as polariton photochemical processes and polariton transport dynamics.