In order to meet the needs of urban landscape and adapt to the trend of sustainable development, it is proposed to replace the traditional steel guardrail with a new type of aluminum alloy guardrail. In order to ensure its good safety performance, its mechanical properties should be evaluated. Based on a practical project, this paper proposes a new type of aluminum alloy guardrail. Through the combination of theoretical analysis and numerical simulation, the bearing capacity of the bolt joints under the collision of automobiles and the safety performance of the railings and columns are comprehensively analyzed. The results show that: for the initial proposed aluminum alloy guardrail scheme, the bolt diameter and the thickness of the flange can be appropriately increased to ensure its good safety performance; when the vehicle collides, the impact force of the improved guardrail and the deformations are in compliance with the specifications and can be applied to actual projects. The research can provide technical support for the promotion and application of similar aluminum alloy guardrails.