With the increasingly serious problem of global climate change, the concept of low-carbon economy has gradually become the development trend of our country. In order to promote the low-carbon construction management of highway tunnels and improve the effect of carbon emission reduction in the process of tunnel construction, the evaluation of low-carbon construction effect in the construction stage of highway tunnels is studied. Firstly, the concept of low-carbon construction of highway tunnel is defined, and the evaluation index system of low-carbon construction effect of highway tunnel is established. Secondly, the evaluation model of low carbon construction effect of highway tunnel is established by using C-CWO operator method improved by normal distribution function-CRITIC method and grey clustering method. Finally, HGS highway tunnel, LH highway tunnel and LB highway tunnel are taken as examples to evaluate the effect of low-carbon construction. The results show that the low-carbon construction effect grade of HGS highway tunnel is grade III, and the low-carbon construction effect grade of LH highway tunnel and LB highway tunnel is grade IV, which provides a reference for the evaluation of low-carbon construction effect of highway tunnel.